Multifunction wafer and film frame handling system

ABSTRACT

A multifunction wafer and film frame handling system includes a wafer table assembly having a wafer table providing an ultra-planar wafer table surface configured for carrying a wafer or a film frame, and at least one of: a flattening apparatus configured for automatically applying a downward force to portions of a warped or non-planar wafer in a direction normal to the wafer table surface; a displacement limitation apparatus configured for automatically constraining or preventing uncontrolled lateral motion of a wafer relative to the wafer table surface after cessation of an applied negative pressure and application of a positive pressure to the underside of the wafer via the wafer table; and a rotational misalignment compensation apparatus configured for automatically compensating for a rotational misalignment of a wafer mounted on a film frame.

TECHNICAL FIELD

Aspects of the present disclosure are directed to a system and methodcapable of handling both wafers and wafers mounted on film frames in amanner that facilitates accurate, high throughput inspection processes.Particular embodiments are configured for automatically (a) remediatinginsufficient vacuum retention of wafers upon a wafer table surface dueto wafer warpage or non-planarity; (b) preventing uncontrolled lateraldisplacement of wafers along the wafer table surface due to vacuum forcecessation and/or air purge application; and/or (c) correcting orcompensating for rotational misalignment of wafers carried by filmframes. Embodiments can also provide a single ultra-planar porous wafertable configured for handling both wafers and film frames.

BACKGROUND

Semiconductor wafer processing operations involve the performance ofvarious types of processing steps or sequences upon a semiconductorwafer upon which a number of die (e.g., a large or very large number ofdie) reside. The geometrical dimensions, linewidths, or feature sizes ofdevices, circuits, or structures on each die are typically very small,for example, micron, submicron, or nanometer scale. Any given dieincludes a large number of integrated circuits or circuit structuresthat are fabricated, processed, and/or patterned on a layer-by-layerbasis, for instance, by way of processing steps performed upon waferssitting on planar wafer surfaces, such that the dies carried by thewafer are collectively subjected to the processing steps.

A wide variety of semiconductor device processing operations involve anumber of handling systems that perform wafer or film frame handlingoperations which involve securely and selectively carrying (e.g.,transporting, moving, displacing, or conveying) wafers or wafers mountedon film frames (hereafter referred to as “film frame” for brevity) fromone position, location, or destination to another, and/or maintainingwafers or film frames in particular positions during wafer or film frameprocessing operations. For instance, prior to the initiation of anoptical inspection process, a handling system must retrieve a wafer or afilm frame from a wafer or film frame source such as a wafer cassette,and transfer the wafer or film frame to the wafer table. The wafer tablemust establish secure retention of the wafer or film frame to itssurface prior to the initiation of the inspection process, and mustrelease the wafer or film frame from its surface after the inspectionprocess is complete. Once the inspection process is complete, a handlingsystem must retrieve the wafer or film frame from the wafer table, andtransfer the wafer or film frame to a next destination, such as a waferor film frame cassette or another processing system.

Various types of wafer handling systems and film frame handling systemsare known in the art. Such handling systems can include one or moremechanical or robotic arms configured for performing wafer handlingoperations which involve the transfer of wafers to and the retrieval ofwafers from a wafer table; or performing film frame handling operationswhich involve the transfer of film frames to and the retrieval of filmframes from a wafer table. Each robotic arm includes an associated endeffector which is configured for retrieving, picking up, holding,transferring, and releasing a wafer or a film frame by way of theapplication and cessation of vacuum force relative to portions of thewafer or film frame, in a manner understood by one of ordinary skill inthe relevant art.

A wafer table itself can be viewed or defined as a type of handlingsystem, which must reliably, securely, and selectively position and holda wafer or film frame on a wafer table surface while displacing thewafer or film frame relative to elements of a processing system, such asone or more light sources and one or more image capture devicescorresponding to an optical inspection system. The structure of a wafertable can significantly impact whether an inspection system can achievea high average inspection throughput, as further detailed below.Furthermore, the structure of a wafer table, in association with thephysical characteristics wafers and the physical characteristics of filmframes, greatly impacts the likelihood that an optical inspectionprocess can reliably generate accurate inspection results.

With respect to the generation of accurate inspection results, during anoptical inspection process, a wafer or a film frame must be securelyretained upon the wafer table. Additionally, the wafer table mustdispose and maintain the upper or top surface of the wafer or film framein a common inspection plane, such that the surface areas of all waferdie, or as many wafer die as possible, collectively reside in thiscommon plane, with minimum or negligible deviation therefrom. Moreparticularly, the proper or accurate optical inspection of die at veryhigh magnification requires a wafer table to be very flat, preferablywith a planarity having a margin of error of less than ⅓ of the depth offocus of the image capture device. If the depth of focus of an imagecapture device is, for instance, 20 μm, a corresponding wafer tableplanarity error cannot exceed 6 μm.

For handling die of very small size (eg. 0.5×0.5 mm or smaller) and/orthickness (50 μm or less—e.g., carried by a very thin and/or flexiblewafer or substrate), this planarity requirement becomes even morecritical. For wafers that are very thin, it is important for the wafertable to be ultra-planar, otherwise it is easy for one or more die onthe wafer or film frame to become positioned out of the depth of focus.One of ordinary skill in the art will recognize that the smaller thedie, the higher the magnification required, and hence the narrower theband of depth of focus in which the inspection plane must lie.

With such planarity outlined aforesaid, a wafer placed on the wafertable will lie flatly on the wafer table surface, the wafer squeezingout substantially all the air beneath it. The difference in atmosphericpressure between the top and bottom surface of the wafer when the waferis disposed upon the wafer table results in a large force appliedagainst the top surface of the wafer due to atmospheric pressure,holding the wafer down strongly or reasonably strongly upon the wafertable. As pressure is a function of surface area, the larger the size ofthe wafer, the greater the force applied downwards on the wafer. This iscommonly referred to as the “inherent suction force” or “natural suctionforce” on the wafer. The flatter the wafer table surface, the greaterthe natural suction force, up to the limit defined by the finite surfaceof the wafer. However, the strength of such suction force depends on howflat the wafer table surface is.

Some wafer tables are not that flat and may have other grooves or holeson its surface resulting in reduced suction force. As the wafer tablewill be repeatedly accelerated over short distances during inspection ofeach die, and a high vacuum force is often applied through the wafertable to the wafer table surface to the underside of the wafer to ensurethat the wafer remains as planar as possible and does not move duringinspection; this is notwithstanding the presence of such natural suctionforce.

Various types of wafer table structures have been developed in attemptsto securely hold wafers or film frames during wafer or film frameinspection operations, and reliably maintain a maximum number of die ina common plane during inspection operations. However not one designexists that will allow the wafer handling system to handle both wafersand sawn wafers mounted on film frames without one or more of theproblems described below. A brief description will be made of each typeof existing design and their associated problems.

Several types of wafer chucks have been or are currently in use. In thepast, wafers were smaller (e.g., 4, 6, or 8 inches) and significantlythicker (particularly in relation to their overall surface areas, e.g.,on a wafer thickness normalized to wafer surface area basis), and eachdie size was larger. Present-day wafer sizes are typically 12 or 16inches, yet the thickness of these processed wafers have been decreasingin relation to their increasing size (for instance, thicknesses of0.70-1.0 mm for 12-inch wafers prior tothinning/backgrinding/backlapping, and 50-150 μm followingthinning/backlapping are common), and die sizes (e.g., 0.5-1.0 mmsquare), respectively. Standard wafer sizes can be expected to furtherincrease over time. Additionally, thinner and thinner wafers can beexpected to be processed each year in response to the increasing demandsand requirements of electronics and mobile phone manufacturers forthinner die/thinner components to fit into slim-built electronic devices(e.g., flat screen televisions, mobile phones, notebook computers,tablet computers, etc.). As will be explained, these factors contributeto the increasing deficiencies of current designs of wafer table tohandle both wafers and film frames.

Historically, and even presently, many wafer chucks have been made of ametal such as steel. Such metal wafer chucks are inlaid with a networkof grooves, usually circular grooves that are intersected by groovesradiating linearly from a central location. Through such grooves, vacuumforce can be applied to the underside of the wafer, which interfaceswith the wafer table surface, in order to facilitate secure retention ofthe wafer against the wafer table surface. In many wafer table designs,such grooves are arranged in concentric circles of increasing size.Depending on the size of the wafer, one or more grooves would be coveredby a wafer when the wafer is disposed upon the wafer table surface.Vacuum can be activated through the grooves covered by the wafer to holdthe wafer down during processing operations, such as wafer inspectionoperations. After inspection, the vacuum is deactivated and ejector pinsare deployed to lift the wafer off of the wafer table surface, such thatthe wafer can be retrieved or removed by an end effector. As there arelinear grooves radiating from the centre of the metal wafer tablesurface, once the vacuum is deactivated, the residual suction forceassociated with application of the vacuum force to the underside of thewafer is quickly dissipated. Thicker wafers are more amenable toapplication of significant force applied through the ejector pins tolift the wafer (against any residual suction force, if any) withoutbreaking.

As indicated above, increasingly wafers manufactured today are thinneror much thinner than before (e.g., present wafer thicknesses can be asthin as 50 μm), and each die thereon is also increasingly smaller insize (e.g., 0.5 mm square) than in the past. Technological progressionresults in smaller die sizes and thinner die, which pose a problem forhandling wafers by way of existing wafer table designs. Very often,backlapped/thinned or sawn wafers (hereafter simply “sawn wafers”)having die that are very small in size and/or which are very thin aremounted on film frames for processing. Conventional metal wafer tablesare not suitable for use with film frames having sawn wafers mountedthereto for a number of reasons.

Bearing in mind that inspection of die involves very high magnification,the higher the magnification, the narrower an acceptable depth of focusband, range, variance, or tolerance will be for accurate inspection. Diethat are not in the same plane are likely to be out of the depth offocus of an image capture device. As indicated above, the depth of focusof a modern image capture device for wafer inspection typically rangesfrom 20-70 μm or smaller, depending on the magnification. The presenceof grooves on the wafer table surface presents problems particularlyduring the inspection of sawn wafers mounted on film frames (with smalldie sizes) on such systems.

The presence of grooves results in the sawn wafers with small die sizesnot sitting properly or uniformly on the wafer table surface. Moreparticularly, in regions where there are grooves (and there can bemany), the film frame's film can slightly sag into the grooves,resulting in the whole wafer surface lacking collective or commonplanarity across all die, which is critical for optical inspectionoperations. This lack of planarity becomes more pronounced for small orvery small die of sawn wafers. Furthermore, the presence of a groove cancause die to be displaced at an angle relative to a common dieinspection plane, or cause the die to sag and sit at one or moredifferent and lower planes. Furthermore, light shining on tilted diewhich have sagged into grooves will reflect light away from the imagecapture device, such that the capture of an image corresponding to atilted die will not contain or convey precise details and/or features ofone or more regions of interest on the die. This will adversely affectthe quality of images captured during inspection, which can lead toinaccurate inspection results.

Several prior approaches have attempted to address the aforementionedproblems. For instance, in one approach a metal wafer table supportincludes a network of grooves. A flat metal plate is placed on top ofthe network of grooves. The metal plate includes many small or verysmall vacuum holes that allow vacuum to be applied through theperforations against a wafer or sawn wafer. Depending on the size ofwafer under consideration, an appropriate pattern or number ofcorresponding grooves will be activated. While multiple small or verysmall vacuum holes can increase the likelihood that die can becollectively maintained in the same inspection plane, collective dieplanarity problems are still not effectively or completely eliminateddue to continuing technological evolution that results in smaller andsmaller die sizes and decreasing die thicknesses over time Such designsalso include multiple sets of ejector pin triplets corresponding todifferent wafer sizes, i.e., multiple distinct sets of three ejectorpins corresponding to multiple standard wafer sizes that the wafer tableis capable of carrying. The presence of numerous holes for ejector pinscan also present, and quite possibly worsen, collective die planarityproblems when inspecting die carried on film frames, for reasonsanalogous to those set forth above.

Some manufacturers use wafer table conversion kits, in which a metalwafer table with grooves is used for handling whole wafers, and a metalwafer table cover with many very small openings is used for film framehandling. Unfortunately, conversion kits require inspection systemdowntime due to the fact that conversion from one type of wafer table toanother, and post-conversion wafer table calibration, is time consumingand done manually. Such downtime adversely affects average systemthroughput (e.g., overall or average throughput with respect to bothwafer and film frame inspection operations considered in sequence ortogether), and hence inspection systems that require wafer tableconversion kits are undesirable.

Other wafer table designs, such as described in U.S. Pat. No. 6,513,796,involve a wafer table receptacle that allows for different central wafertable inserts depending on whether wafers or film frames are beingprocessed. For wafer inspection, the insert is typically a metal platewith annular rings having vacuum holes for activation of vacuum. Forfilm frames, the insert is a metal plate having many fine holes forvacuum activation, which can still give rise to collective dienonplanarity as described above.

Still other wafer table designs, such as disclosed in U.S. PatentApplication Publication 2007/0063453, utilize a wafer table receptaclehaving a plate type insert consisting of a porous material in whichdistinct regions are defined by annular rings made of a thin filmmaterial. Typically, such wafer table designs are complex in constructand involves a delicate and complex manufacturing process, and hencedifficult, time consuming, or costly to manufacture. Moreover, suchdesigns can utilize metal annular rings to facilitate regional vacuumforce control across the wafer table surface in accordance with wafersize. Metal annular rings can require undesirably long planarizationtimes, or damage a polishing device that is used to polish the wafertable surface when planarizing the wafer table surface. Furthermore,metal rings can give rise to nonplanarity due to differential materialpolishing characteristics across the wafer table surface, and thereforemetal annular rings are unsuitable for modern optical inspectionprocesses (e.g., particularly involving sawn wafers mounted on filmframes).

Unfortunately, prior wafer table designs are (a) unnecessarilystructurally complex; (b) difficult, expensive, or time consuming tofabricate; and/or (c) unsuitable for various types of wafer processingoperations (e.g., die inspection operations, particularly when die arecarried by a film frame) as a result of insufficient wafer table surfaceplanar uniformity in view of technological evolution that continues togive rise to smaller and smaller wafer die sizes and/or progressivelydecreasing wafer thicknesses. A need clearly exists for a wafer tablestructure and an associated wafer table manufacturing technique thatthat will enable the wafer table to handle both wafers and sawn wafersand which overcomes one or more of the foregoing problems or drawbacks.

In addition to the above aspects of wafer table design that can impactthe accuracy of wafer and film frame inspection as well as averageinspection throughput, multiple other types of wafer or film framehandling problems can exist, which can adversely affect wafer or filmframe inspection operations. Such problems and prior art solutionsthereto are detailed hereafter.

Wafer—Wafer Table Retention Failure Due to Wafer Non-Planarity

One type of wafer handling problem arises as a result of wafernon-planarity or warpage. This problem arises from a number of factors,including (a) the increasing size of wafers being manufactured; (b) thedecreasing thickness of wafers being handled; and (c) the manner inwhich wafers are handled or stored prior to and—after processing. Priorto and after processing such as optical inspection, wafers are held attheir edges in a cassette. Given the increasing diameter and thinness ofwafers, and the manner in which wafers are held in the cassette, saggingof a wafer near its center, or wafer warpage, is not uncommon. Inaddition, during backlapping processes to thin the wafer to requireddimensions, the backlapping process can cause the wafer to have areverse warp, although this problem is less common.

When a non-planar wafer rests upon a wafer table surface, a vacuum forceapplied through the wafer table surface which is intended to securelyhold the entire bottom surface of the wafer against the wafer tablesurface will only weakly hold a portion of the bottom wafer surface. Asthe other portions of the wafer will reside above the wafer tablesurface and vacuum that is applied through the wafer table will leak andany residual vacuum force applied would be very weak. In such asituation, the wafer will not be held down securely and furthermore sucha warped wafer 10 cannot, typically, be reliably inspected or tested.

Prior approaches directed to ensuring that the entire surface area of awafer is securely held upon a wafer table surface involve automaticallyhalting inspection system operation when an insufficient vacuumretention force (or vacuum leakage that is below a minimum vacuumretention threshold value) is detected, until an inspection systemoperator or user manually intervenes. To solve the problem, theinspection system operator manually presses the wafer against the wafertable surface, until vacuum force applied through the wafer tablesurface engages the wafer's entire surface area and securely retains thewafer against the wafer table surface. Such automatic halting ofinspection system operation as a result of insufficient vacuum retentionof the wafer upon the wafer table surface can only be resumed after userintervention to manually correct the problem. Such downtime adverselyimpacts system throughput.

Unpredictable/Uncontrollable Lateral Wafer Displacement Following VacuumForce Cessation

Typically, for inspection of wafers, the following steps occur to placea wafer on a wafer table: (a) the wafer is retrieved from a cassette andsent to a wafer (pre)aligner; (b) the wafer aligner serves to properlyorientate the wafer for inspection; (c) after wafer alignment iscompleted, an end effector conveys the wafer to a predetermined positionwhere its center coincides with the center of the wafer table; (d)ejector pins are activated to receive the wafer; (e) the end effectorlowers the wafer onto the ejector pins before retracting; and (f) theejector pins then lower the wafer onto the wafer table for inspectionwhile vacuum is applied to hold the wafer down for inspection.

When inspection is completed, (a) vacuum is deactivated; (b) the waferis lifted up by the ejector pins; (c) the end effector slides beneaththe wafer and lifts up the wafer; and (d) the end effector transfers theinspected wafer back to a cassette, and puts the wafer into thecassette.

It is pertinent to note that to enable the effector to place the waferinto the cassette, it is important that the wafer remains in apredetermined position, and has not changed its position, relative tothe end effector from the time it was placed on the wafer table. Thismeans that the wafer must not move from the moment it is placed on thetable. If the wafer is significantly or seriously out of positionrelative to the end effector, there is a risk that the wafer can dropduring conveyance, or be damaged when the end effector tries to push theoff-positioned wafer into the cassette. To prevent these mishaps, whenthe wafer is finally picked up by the effector after inspection, thewafer should, relative to the end effector, be in the same position asit was when the wafer was placed on the wafer table prior to the startof inspection. To hold the wafer in its position upon placement by theend effector, vacuum through the grooves is activated in addition to thenatural suction that results when the whole or parts of the wafer sitsflatly on the wafer table.

In certain situations, after the application of vacuum force or negativepressure to the underside of a wafer has ceased, the wafer can slidelaterally along the wafer table surface as a consequence of subsequentevents or process steps. Unpredictable lateral motion of the wafercauses the wafer to move or translate to a different position from theposition at which the wafer was originally placed upon the wafer tableprior to or at the start of inspection (i.e., the wafer laterally slidesaway from a reference wafer table position relative to which theeffector deposits and retrieves the wafer). Consequently, when theeffector retrieves a wafer that is unreliably or unpredictablymispositioned as a result of such lateral motion, there is a risk thatthe wafer will be dropped or damaged when the effector attempts to loadthe out-of-position wafer 10 back into a wafer cassette.

Prior approaches for managing unintended lateral wafer displacementrelative to a wafer table surface following vacuum force cessationinvolve manual intervention, which again results in the interruption ofinspection or test system operations, adversely impacting productionthroughput.

Wafer—Film Frame Rotational Misalignment

At a particular stage of wafer manufacturing, wafers may be mounted onfilm frames. For instance, when wafers are to be sawn, they are usuallymounted on film frames. After being sawn, the sawn wafers on film frameare further inspected for cosmetic and/or other types of defects. FIG.1A is a schematic illustration of a wafer 10 mounted on a film frame 30,which carries the wafer 10 by way of a thin material layer or film 32that typically includes an adhesive or tacky side to which the wafer 10is mounted, in a manner readily understood by one of ordinary skill inthe art. The wafer 10 includes a number of die 12, which are separatedor delineated from each other by horizontal gridlines 6 and verticalgridlines 8 that are produced or which become evident duringmanufacture. Such horizontal and vertical gridlines 6, 8 correspond toor delineate horizontal and vertical sides 11, 16 of the die,respectively. One of ordinary skill in the art will understand that awafer 10 typically includes at least one reference feature 11, forinstance, a notch or a straight portion or “flat” segment on anotherwise circular periphery, to facilitate wafer alignment operations.One or ordinary skill in the relevant art will further understand thatthe film frame 30 includes a number of registration or alignmentfeatures 34 a-b to facilitate film frame alignment operations. The filmframe 30 can also include a number of other reference features, such as“flats” 35 a-d.

With respect to optical inspection, die 12 on the wafer 10 areautomatically inspected or examined in accordance with inspectioncriteria that facilitate the identification of cosmetic or other (e.g.,structural) defects on the die 12. Die 12 which meet the inspectioncriteria, as well as die which fail to meet the inspection criteria, canbe tracked or categorized in accordance with “pass” or “fail”designations, respectively. Die 12 that successfully meet all inspectioncriteria are suitable for further processing or incorporation into anintegrated circuit package, whereas die 12 that fail to meet allinspection criteria can be (a) discarded; (b) analyzed for determiningfailure cause(s) and preventing future failures; or (c) in certainsituations, reworked/reprocessed.

Optical inspection involves directing illumination at individual die 12or an array of die 12; capturing illumination reflected from the die 12using an image capture device and generating image data corresponding tothe die 12; and performing image processing operations upon the imagedata to determine whether one or more types of defects are present onthe die 12. Optical inspection is typically performed “on-the-fly” whilethe wafer 12 is in motion, such that the die 12 carried by the wafer 12are continuously moving relative to the image capture device duringimage capture operations.

Inspection of an entire wafer 10 requires the generation of aninspection result (e.g., a pass/fail result) corresponding to each die12 on the wafer 10. Before an inspection result corresponding to anygiven die 12 can be generated, the entire surface area of the die 12must first be completely captured. In other words, complete inspectionof any given die 12 requires that the die's entire surface area mustfirst be completely captured by the image capture device, and image datacorresponding to the entire surface area of each of the die 12 must begenerated and processed. If image data corresponding to the die's entiresurface area has not been generated, image processing operationscorresponding to the die 12 cannot be completed, and an inspectionresult cannot be generated, until the capture of a set of imagesencompassing the entire surface area of the die 12, or an “entire-dieimage,” has occurred. Therefore, if image data corresponding to theentire surface area of a die 12, or entire-die image data, has not beengenerated, the generation of an inspection result for the die 12 isunnecessarily delayed, which adversely affects inspection processthroughput.

The greater the number of image capture operations required tocompletely capture the entire die image for image processing, the lowerthe throughput for inspection. It stands to reason that in order tomaximize inspection process throughput, every die's entire surface areashould preferably be captured in as few images as possible.

Error in the orientation of the wafer 10 can arise during the mountingof the wafer 10 on a film frame 30. In general, the error in wafermounting relates to a wafer flat or notch 11 not aligning properly withrespect to a given film frame reference feature, such as a film frameflat 35 a. FIG. 1B is a schematic illustration of a wafer 10 that isrotationally misaligned relative to a film frame 30 that carries thewafer 10. It can be clearly seen that the wafer 10 shown in FIG. 1Bbears a significantly different rotational orientation relative to itsfilm frame 30 than the wafer 10 shown in FIG. 1A bears in relation toits film frame 30. More particularly, it can be seen from FIG. 1B thatwith respect to a horizontal reference axis 36 and/or a vertical axis 38defined parallel to and perpendicular to a first film frame flat 35 a,respectively, a pair of reference horizontal and vertical wafergridlines 6, 8 are rotated, angularly offset, or misaligned by an angleθ compared to the wafer 10 shown in FIG. 1A.

In other words, for the wafer 10 shown in FIG. 1A, the angle θ, whichindicates an angular extent to which a wafer gridline 6, 8 has beenrotated away from a reference axis 36, 38 having a predeterminedorientation relative to the first film frame flat 35 a, is approximatelyzero. For the wafer 10 shown in FIG. 1B, the wafer-to-film framemisalignment angle is θ non-zero. As wafer size increases, andparticularly for larger wafer sizes (e.g., 12 inches or greater), therotational misalignment of a mounted wafer 10 vis-à-vis the film frame30 typically creates problems during inspection of the wafer 10 mountedthereon, as further detailed hereafter.

During the capture of a given image of a die 12, an inspection system'simage capture device can capture illumination reflected from only thoseportions of the die's surface area which are disposed within the imagecapture device field of view (FOV). Portions of the die's surface areawhich fall outside of the image capture device FOV cannot be captured aspart of this image, and must be captured as part of another image. Asindicated above, the maximization of inspection process throughputrequires that the entire surface area of every die 12 on the wafer 10 becaptured in as few images as possible. When multiple image captureoperations are required to generate image data corresponding to a die'sentire surface area, the generation of an inspection result for the die12 is delayed, which adversely affects throughput. Each die 12 on thewafer 10 must therefore be properly aligned relative to the imagecapture device FOV in order minimize the number of image captureoperations required to generate entire-die image data for all die 12 onthe wafer 10, in order to maximize inspection process throughput.

Proper alignment of the die 12 relative to the image capture device FOVcan be defined as a situation in which any rotational or angularmisalignment of the die 12 relative to the image capture device FOV issufficiently small, minimal, or negligible that the die's entire surfacearea will fall within the FOV. FIG. 2A is a schematic illustration of adie 12 that is properly positioned or aligned relative to an imagecapture device field of view (FOV) 50. As clearly indicated in FIG. 2A,under conditions of proper die alignment relative to the FOV 50, ahorizontal border or side 14 of the die 12 is aligned substantiallyparallel to an FOV horizontal axis X₁, and a vertical border or side 16of the die 12 is aligned substantially parallel to an FOV vertical axisY₁. Consequently, the entire surface area of such a die 12 falls withinthe FOV 50, and the entire surface area of the die 12 can be captured bythe image capture device in a single image capture event, operation, or“snap.”

FIG. 2B is a schematic illustration of a die 12 that is improperlypositioned or which is misaligned relative to an image capture deviceFOV 50. FIG. 2B clearly indicates that the horizontal and vertical sidesof the die 14, 16 are rotated or angularly offset from the FOVhorizontal axis X₁ and the FOV vertical axis Y₁, respectively, andportions of the die's surface area fall outside of the FOV 50. Becauseof such misalignment of the die 12 relative to the FOV 50, thegeneration of image data corresponding to the entire surface area of thedie 12 requires the capture of multiple images that capture differentportions of the die 12, resulting in reduced inspection processthroughput. More particularly, as shown in FIG. 2C, up to four imagesmay be required to capture the entire surface area of such arotationally misaligned die 12, depending upon the extent of the die'smisalignment relative to the FOV.

When film frames are handled, typically a mechanical film frameregistration procedure must take place. Usually, the film frameregistration procedure occurs when the film frame is placed on the wafertable. In some systems, such as that described in Singapore PatentApplication No. 201103524-3, entitled “System and Method for Handlingand Aligning Component Panes such as Wafers and Film Frames,” filed on12 May 2011, a mechanical film frame registration can take place beforeplacement of the film frame on the wafer table, such as when an endeffector that carries the film frame causes a set of film framealignment features 34 a-b to engage with film frame registrationelements or structures prior to placement of the film frame on the wafertable.

A mechanical film frame registration procedure involves a certain amountof handling time. However, the film frame registration proceduretypically ensures that the film frame 30 is properly aligned orregistered with respect to the image capture device FOV. However thisassumes that the wafer was properly mounted on the film frame in thefirst place, which is not always the case. Where the wafer mounted onthe film frame has a rotational misalignment, it can give rise toproblems and delays in inspection, adversely affecting throughput aselaborated upon below.

The film frame registration procedure occurs by way of mating engagementbetween film frame registration features 34 a-b and one or more filmframe registration elements, which are conventionally carried by a wafertable assembly. After a film frame 30 has been registered, die 12 on thewafer 10 mounted to the film frame 30 are expected to be properlyaligned with respect to the image capture device FOV. However, if morethan a slight or minimal amount of rotational or angular misorientationof the wafer 10 mounted to the film frame 30 exists, the die 12 will notbe properly aligned relative to the image capture device FOV. Ittherefore stands to reason that the extent of any rotationalmisalignment of a wafer 10 that occurs during the mounting of the wafer10 to a film frame 30 can adversely affect the number of images requiredto capture the entire surface area of each die 12 on the wafer 12, andhence the extent of any rotational misalignment of the wafer 10 relativeto the film frame 30 can adversely affect inspection throughput.

Proper alignment of the wafer 10 relative to its film frame 30 ensuresproper alignment of the die 12 relative to the image capture device FOV50. Proper alignment of the wafer 10 relative to its film frame 30 canbe defined as a situation in which one or more wafer gridlines 6, 8 havea standard predetermined alignment relative to one or more film framestructural features such as film frame flats 35 a-d and/or the imagecapture device FOV, such that the each die 12 is positioned relative tothe image capture device FOV in the manner shown in FIG. 2A (i.e., eachdie's horizontal and vertical sides 14, 16, with the FOV horizontal andvertical axes X₁ and Y₁). Such alignment of the wafer 10 relative to thefilm frame 30 minimizes the number of image capture operations requiredto capture each die's entire surface area, thereby maximizing inspectionprocess throughput.

To further illustrate, FIG. 2D is a schematic illustration of a wafer 10that is properly mounted on and aligned relative to a film frame 30, andan inspection process wafer travel path along which an image capturedevice captures an image of the entire surface area of each die 12within successive rows of die 12 on the wafer 10. Two representativerows of die 12 are identified in FIG. 2D, namely, row “A” die 12 and row“B” die. Because this wafer 10 is properly aligned relative to its filmframe 30, during the inspection process the entire surface area of eachdie 12 within row “A” can be captured in a single corresponding image(e.g., while the wafer 10 is in motion, or “on-the-fly”). Following thecapture of the images corresponding to the row “A” die, the wafer 10 isimmediately positioned such that the surface area of a row “B” die 12that is closest to the last considered row “A” die 12 can be captured bythe image capture device, and inspection continues along an oppositedirection of travel. Thus, the inspection travel path is “serpentine.”Once again, because this wafer 10 is properly aligned with respect toits film frame 30, during the inspection process the entire surface areaof each die 12 within row “B” can be captured in a single correspondingimage. Inspection of the entire wafer 10 in this manner, when the wafer10 is properly aligned relative to its film frame 30, results in maximuminspection process throughput.

FIG. 2E is a schematic illustration of a wafer 10 that is rotationallymisaligned relative to a film frame 30 that carries the wafer, and aninspection process wafer travel path along which an image capture devicecaptures less than the entire surface area of each die 12 withinsuccessive rows of die 12 on the wafer 10 during any single imagecapture event. During an optical inspection process, as a result of suchwafer-to-film frame rotational misalignment, the horizontal and verticalsides 14, 16 of the die 12 carried by the wafer 10 will be rotationallyoffset from the FOV horizontal and vertical axes X₁ and Y₁,respectively, even when the film frame 30 itself is properly registeredwith respect to the image capture device. Consequently, the entiresurface area of a given die 12 may not fall within the image capturedevice FOV 50, and multiple individual images will be required tocapture a given die's entire surface area. Because an inspection resultcannot be generated for the die 12 until after multiple images havecaptured the die's entire surface area, the generation of an inspectionresult corresponding to the die 12 is undesirably delayed.

Analogous considerations to those described above apply when inspectioninvolves a group of die 12. FIG. 2F is a schematic illustration of a diearray 18 in which the collective surface area of all die 12 within thedie array 18 is smaller than an image capture device FOV 50, and the diearray 18 is properly aligned relative to the image capture device FOV 50because the horizontal and vertical sides 14, 16 of each die 12 withinthe die array 18 are substantially parallel to the FOV horizontal axisX₁ and the FOV vertical axis Y₁, respectively. As a result, the entiredie array 18 can be captured as a single image by the image capturedevice, thereby maximizing inspection process throughput. FIG. 2G is aschematic illustration of a die array 18 for which the horizontal andvertical sides 14, 16 of the die 12 within the die array 18 are notproperly aligned with respect to the FOV horizontal and vertical axes X₁and Y₁. Thus, portions of the die array 18 fall outside of the FOV 50.As a result, multiple images of the die array 18 must be captured beforean inspection result can be generated for the die array 18, therebylowering throughput.

Moreover, analogous considerations to those described above also applywhen inspection involves a single (e.g., large) die 12 that, whenproperly aligned relative to the image capture device FOV 50, has asurface area that is larger than the FOV 50. FIG. 2H is a schematicillustration of a die 12 having a surface area that is larger than theFOV 50 of an image capture device. This die 12 is also properly alignedrelative to the FOV 50, because the die's horizontal and vertical sides14, 16 are substantially parallel to the FOV horizontal and verticalaxes X₁ and Y₁, respectively. As a result, the overall surface area ofthe die 12 can be captured in a minimum number of image captureoperations. In this example, the image capture device must capture atotal of 9 images for inspection of the entire surface area of the die12, which occurs by way of successively positioning different portionsof the die's surface area relative to the image capture device, andcapturing an image of each portion of the die's surface area that fallswithin the image capture device FOV 50 during each such relativepositioning.

FIG. 2I is a schematic illustration of a single die 12 such as thatshown in FIG. 2H, which under proper FOV alignment conditions would becompletely inspected through the capture of 9 images, but for whichhorizontal and vertical die side misalignment relative to FOV horizontaland vertical axes X₁ and Y₁ results in portions of the die 12 remainingoutside of the image capture device FOV 50 even after 9 images have beencaptured.

Prior systems and methods rely upon either manual intervention or arotatable wafer table to compensate or correct for rotationalmisalignment between a wafer 10 and a film frame 30. As before, manualintervention adversely affects system throughput. With respect to arotatable wafer table, such a wafer table is configured for selectivelyproviding an amount of rotational displacement that is sufficient tocompensate or substantially compensate for wafer—film frame rotationalmisalignment. The magnitude of misalignment between a wafer 10 and afilm frame 30 can span a significant number of degrees, for instance,10-15 degrees or more, in a positive or negative direction.Unfortunately, a wafer table configured for providing such rotation isundesirably complex from a mechanical standpoint, and correspondinglyexpensive (e.g., prohibitively expensive). Furthermore, the additionalstructural complexity of a wafer table assembly that provides suchrotational wafer table displacement can make it significantly moredifficult to consistently maintain the wafer table surface in a singleplane perpendicular to the optical axis of the image capture deviceduring inspection.

A need exists for a wafer and film frame handling system that provides asingle wafer table structure for handling both wafers and film frames,and which can automatically overcome at least some of the aforementionedproblems arising from wafer warpage, unpredictable lateral wafer motion,and wafer—film frame rotational misalignment, and which can enhance ormaximize inspection process throughput.

SUMMARY

In accordance with an aspect of the present disclosure, a system forhandling wafers and film frames on which wafers or portions thereof aremounted includes a wafer table assembly comprising a wafer tableproviding an ultra-planar wafer table surface (which can include aporous material) configured for carrying a wafer or a film frame, thewafer table assembly configured for applying a negative pressure or apositive pressure to an underside of a wafer or an underside of a filmof a film frame on which the wafer is mounted; and at least one of: (i)a flattening apparatus configured for automatically applying a downwardforce to portions of a warped or non-planar wafer in a direction normalto the wafer table surface in response to a detection of insufficientwafer retention upon the wafer table surface; (ii) a displacementlimitation apparatus configured for automatically constraining orpreventing uncontrolled lateral motion of a wafer relative to the wafertable surface after cessation of an applied negative pressure andapplication of a positive pressure to the underside of the wafer via thewafer table; and (iii) a rotational misalignment compensation apparatusconfigured for automatically compensating for a rotational misalignmentof a wafer mounted on a film frame. The wafer table assembly can excludefilm frame registration elements configured for facilitating film framealignment by way of mating engagement with a set of film frame referencefeatures.

The rotational misalignment apparatus can include a first image capturedevice configured for capturing an image of portions of the wafermounted on the film frame; and a processing unit configured fordetermining an angular extent of rotational misalignment and a directionof rotational misalignment of the wafer mounted on the film frame withrespect to (i) a field of view of the first image capture device and/or(ii) the film frame.

The flattening apparatus eliminates a need for manual intervention whenthe warped or non-planar wafer cannot be reliably retained on the wafertable surface as a result of its warpage or non-planarity. Thedisplacement limitation apparatus eliminates a need for manualintervention in response to uncontrolled lateral displacement of thewafer relative to the wafer table surface after cessation of anapplication of negative pressure to the underside of the wafer. Thedisplacement limitation apparatus can facilitate release of the verythin or ultra-thin wafer from the wafer table surface after anapplication of positive air pressure in a manner that reliably avoidsdamaging a very thin or ultra-thin wafer by preventing uncontrolledlateral displacements of the ultra-thin wafer.

In an embodiment, the system includes a multi-function handlingapparatus having: a main body positionable over the wafer table surfaceand displaceable along a vertical axis that is perpendicular to thewafer table surface; a plurality of capture arms coupled to the mainbody, each capture arm within the plurality of capture arms controllablydisplaceable to multiple distinct positions transverse to and towards oraway from the vertical axis; a set of vacuum elements coupled to theplurality of capture arms and configured for controllably applyingvacuum forces to portions of a periphery of a film frame to facilitatesecure capture of the film frame by the plurality of capture arms; and avertical displacement driver configured for controllably displacing themain body and consequently simultaneously displacing the plurality ofcapture arms along a vertical direction parallel to the vertical axis totransport the film frame to the wafer table surface by directly placingthe film frame thereon. The multi-function handling apparatus canfurther include a rotational misalignment compensation driver configuredfor precisely and simultaneously rotating the plurality of capture armsabout the vertical axis to compensate for a rotational misalignment of awafer mounted on the film frame relative to the film frame and/or afield of view of an image capture device, while the film frame istransported to the wafer table surface.

In an embodiment, the system includes a handling subsystem having: amain body positionable over the wafer table surface and displaceablealong a vertical axis that is perpendicular to the wafer table surface;a plurality of capture arms coupled to the main body, each capture armwithin the plurality of capture arms controllably displaceable tomultiple distinct positions transverse to and towards or away from thevertical axis; and a capture arm tip coupled to each capture arm withinthe plurality of capture arms, each capture arm tip comprising a softand resiliently deformable material, wherein the handling subsystemimplements at least one of the flatting apparatus and the displacementlimitation apparatus; or each of the film frame transport apparatus, theflattening apparatus, the displacement limitation apparatus, and therotational misalignment compensation apparatus.

The plurality of tip elements is displaceable to at least one of: (i) aplurality of engagement assistance positions, each engagement assistanceposition disposing the plurality of tip elements away from each otheracross an area that is slightly less than a standard wafer diameter atthe periphery of a wafer on the wafer table surface; and (ii) aplurality of confinement positions, each confinement position disposinga each tip element within the plurality of tip elements beside and justbeyond the periphery of a wafer on the wafer table surface, wherein eachengagement assistance position corresponds to a different standard waferdimension and each confinement position corresponds to a differentstandard wafer dimension.

The wafer table assembly includes a set of ejector pins displaceablealong a vertical direction perpendicular to the wafer table surface, andthe displacement limitation apparatus can include: a control unitconfigured for controlling: (a) an application of an air puff to theunderside of the wafer essentially immediately after interruption orcessation of the application of the suction force to the underside ofthe wafer, the air puff applied from an air puff onset time to an airpuff cessation time; and (b) activation of the set of ejector pins todisplace the set of ejector pins in an upward direction after a verybrief ejector pin activation delay time following the air puff onsettime to thereby lift the wafer off of the wafer table surface withminimal or negligible lateral displacement as a result of the very briefejector pin activation delay time relative to the air puff onset time,wherein the ejector pin activation delay time is precisely controlledrelative to the air puff onset time such that the wafer is verticallyraised away from the wafer table surface synchronous with the release ofthe wafer from the wafer table surface in response to the air puff. Theejector pin activation delay time is experimentally determined, and/orcan be between 5-50 msec.

In accordance with an aspect of the present disclosure, a process forhandling wafers and film frames on which wafers or portions thereof aremounted, each wafer having a periphery and a surface area, each filmframe including a corresponding film on which a wafer or a portionthereof is mounted and which is supported by the film frame, includes:transporting a wafer to an ultra planar wafer table surfacecorresponding to a wafer table assembly comprising a wafer tableconfigured for applying a negative pressure or a positive pressure to anunderside of a wafer or an underside of a film of a film frame on whichthe wafer is mounted; and at least one of, and possibly each of: (i)automatically remediating a rotational misalignment of a wafer relativeto a film frame on which the wafer is mounted; (ii) automaticallyremediating insufficient retention of the wafer upon the wafer tablesurface due to wafer warpage or non-planarity; and (iii) automaticallypreventing uncontrolled lateral displacement of the wafer relative tothe wafer table surface following interruption or cessation of thesuction force to the underside of the wafer.

The process can further include removing the wafer from the wafer tableby way of elevating a set of ejector pins and an end effector configuredto capture the wafer from the elevated set of ejector pins; and directlyplacing a film frame on the wafer table surface without the use ofejector pins following removal of the wafer from the wafer table withoutconverting the wafer table for film frame handling by way of aconversion kit.

Directly placing the film frame on the wafer table surface can include:positioning a film frame transport apparatus over the film frame, thefilm frame transport apparatus comprising a housing coupled to aplurality of displaceable capture arms, each capture arm coupled to asoft and resiliently deformable tip element, each capture arm fluidlycoupled to a vacuum or negative pressure source; positioning theplurality of capture arms at a film frame capture position correspondingto a standard dimension of the film frame, such that the tip elementsengage with portions of a film frame border; applying a vacuum force ornegative pressure to portions of the film frame border by way of theplurality of capture arms to securely capture the film frame;positioning the captured film frame over the wafer table surface;displacing the captured film frame downward toward the wafer tablesurface until the film frame contacts the wafer table surface; applyinga suction force to an underside of the film corresponding to the filmframe by way of the wafer table; and terminating the application ofvacuum force or negative pressure to portions of the film frame border.

Automatically remediating a rotational misalignment of a wafer relativeto a film frame on which the wafer is mounted can include: capturing animage of portions of the wafer mounted on the film frame using an imagecapture device; determining a rotational misalignment angle and arotational misalignment direction of the wafer relative to the filmframe and/or the image capture device; rotating the film frame acrossthe rotational misalignment angle in a direction opposite to therotational misalignment direction by way of a rotational compensationapparatus separate from the wafer table; and placing the film frame onthe wafer table.

Capturing an image of portions of the wafer can include capturing animage of portions of the wafer using a first image capture device priorto placement of the film frame on the wafer table. Capturing such animage can occur by way of a second image capture device that forms aportion of an inspection system after placement of the film frame on thewafer table.

Automatically remediating insufficient retention of the wafer upon thewafer table surface can include: automatically detecting insufficientretention of the wafer upon the wafer table surface; and responsivelyapplying a set of downward forces to portions of an exposed uppersurface of the wafer concurrent with the application of the suctionforce to the underside of the wafer to facilitate secure retention ofthe wafer upon the wafer table surface. Applying the set of downwardforces can include: positioning a flattening apparatus above the wafer,the flattening apparatus comprising a housing coupled to a plurality ofdisplaceable arms, each arm within the plurality of arms coupled to atip element comprising a soft and resiliently deformable material;positioning the tip elements in accordance with an engagement assistanceposition corresponding to a dimension of the wafer upon the wafer table,such that a portion of each tip element is disposed directly over theexposed upper surface of the wafer for engaging with or contacting aportion of the exposed surface of the wafer; and displacing the tipelements disposed over the exposed upper surface of the wafer downwardtoward the wafer table surface.

Such automatic remediation of insufficient wafer retention upon thewafer table surface can further include: detecting secure retention ofthe wafer upon the wafer table surface by way of the vacuum gauge; andterminating the application of the set of downward forces to portions ofthe exposed upper surface of the wafer in response to secure retentionof the wafer on the wafer table surface.

Automatically preventing uncontrolled lateral displacement of the waferrelative to the wafer table surface can include positioning aconfinement apparatus above the wafer, the confinement apparatuscomprising a housing coupled to a plurality of displaceable arms, eacharm within the plurality of arms coupled to a tip element comprising asoft and resiliently deformable material; positioning the tip elementsin accordance with a confinement position corresponding to a dimensionof the wafer upon the wafer table, such that a portion of each tipelement is disposed just beyond the periphery of the wafer; interruptingor terminating the application of suction force to the underside of thewafer; and activating a set of ejector pins corresponding to the wafertable in an upward direction to elevate the wafer away from the wafertable surface.

Alternatively, automatically preventing uncontrolled lateraldisplacement of the wafer relative to the wafer table surface caninclude: interrupting or terminating the application of suction force tothe underside of the wafer; applying an air puff to the underside of thewafer essentially immediately after interruption or cessation of theapplication of the suction force to the underside of the wafer, the airpuff applied from an air puff onset time to an air puff cessation time;and activating a set of ejector pins corresponding to the vacuum tableto displace the set of ejector pins in an upward direction after a verybrief ejector pin activation delay time following the air puff onsettime to thereby lift the wafer off of the wafer table surface withminimal or negligible lateral displacement as a result of the very briefejector pin activation delay time relative to the air puff onset time,wherein the ejector pin activation delay time is precisely controlledrelative to the air puff onset time such that the wafer is verticallyraised away from the wafer table surface synchronous with the release ofthe wafer from the wafer table surface in response to the air puff.

In accordance with an aspect of the present disclosure, a process forhandling a wafer in association with an inspection process performableby an inspection system includes: retrieving the wafer from a wafersource; transporting the wafer to a wafer prealigner; disposing thewafer on a wafer table surface provided by a wafer table followingprealignment of the wafer; applying a negative pressure to an undersideof the wafer; and at least one of: (i) automatically remediatinginsufficient retention of the wafer upon the wafer table surface due towafer warpage or non-planarity by way of: detecting whether the wafer issecurely retained upon the wafer table surface prior to the initiationof the inspection process, and automatically applying a downward forceto portions of the wafer until secure retention of the wafer upon thewafer table surface is detected; (ii) automatically preventinguncontrolled lateral displacement of the wafer along the wafer tablesurface following the inspection process as a result of cessation of theapplication of the negative pressure to the wafer by way of:automatically confining the wafer to reside within a confinementposition on the wafer table, or coordinating the cessation of theapplication of the negative pressure to the underside of the wafer withan application of an air puff to the underside of the wafer and anactivation of a set of ejector pins that is vertically displaceablerelative to the wafer table surface, such that the wafer is verticallyraised away from the wafer table surface synchronous with the release ofthe wafer from the wafer table surface in response to the air puff; andretrieving the wafer from the wafer table and transferring the wafer toa wafer destination.

In accordance with an aspect of the present disclosure, a process forhandling a film frame in association with an inspection processperformable by an inspection system includes: retrieving the film framefrom a film frame source; capturing an image of portions of the wafermounted to the film frame using a first image capture device;determining by way of image processing operations an angularmisalignment magnitude and an angular misalignment direction ofrotational misalignment of the wafer relative to the film frame and/orthe first image capture device; transferring the film frame to amulti-function handling apparatus configured for (i) automaticallyrotating the film frame on which the wafer is mounted to compensate forrotational misalignment of the wafer relative to the film frame and/orthe first image capture device, and (ii) directly placing the film frameon a wafer table surface of a wafer table corresponding to theinspection system, wherein the multi-function handling apparatus isseparate from the inspection system; initiating the inspection processusing a second image capture device corresponding to the inspectionsystem following compensation for the rotational misalignment of thewafer relative to the film frame and/or the first image capture deviceby the multi-function handling apparatus; and transferring the filmframe to a film frame destination following completion of the inspectionprocess. The process further includes rotating the film frame across theangular misalignment magnitude in a direction opposite to the angularmisalignment direction while the multi-function handling apparatustransfers the film frame to the wafer table surface.

Capturing an image of portions of the wafer mounted on the film frameusing the first image capture device can occur (a) while the film frameis being carried by an end effector of a robotic arm toward themulti-function handling apparatus, (b) after the film frame has beentransferred to the multi-function handling apparatus and prior toplacement of the film frame on the wafer table surface, or (c) after thefilm frame has been placed on the wafer table surface.

Transferring the film frame to the film frame destination can includedirectly removing the film frame from the wafer table surface by way ofthe multi-function handling apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A is a schematic illustration of a wafer mounted on a film frame,which carries the wafer by way of a thin material layer or film thatincludes an adhesive or tacky side to which the wafer is mounted.

FIG. 1B is a schematic illustration of a wafer that is rotationallymisaligned relative to a film frame that carries the wafer.

FIG. 2A is a schematic illustration of a die that is properly positionedor aligned relative to an image capture device field of view (FOV).

FIG. 2B is a schematic illustration of a die that is improperlypositioned or misaligned relative to an image capture device FOV.

FIG. 2C is a schematic illustration indicating that up to four imagesmay be required to capture the entire surface area of a rotationallymisaligned die such as that shown in FIG. 2B, depending upon the extentof the die's misalignment relative to the FOV.

FIG. 2D is a schematic illustration of a wafer that is properly mountedon and aligned relative to a film frame, and an inspection process wafertravel path along which an image capture device captures an image of theentire surface area of each die within successive rows of die on thewafer.

FIG. 2E is a schematic illustration of a wafer 10 that is rotationallymisaligned relative to a film frame, and an inspection process wafertravel path along which an image capture device captures images of lessthan the entire surface area of each die within successive rows of dieon the wafer.

FIG. 2F is a schematic illustration of a die array in which thecollective surface area of all die within the die array is smaller thanan image capture device FOV, and the die array is properly alignedrelative to the FOV because horizontal and vertical sides of each diewithin the die array are substantially parallel to FOV horizontal andvertical axes axis X₁ and Y₁, respectively.

FIG. 2G is a schematic illustration of a die array for which thehorizontal and vertical sides of the die within a die array are notproperly aligned with respect to FOV horizontal and vertical axes X₁ andY₁.

FIG. 2H is a schematic illustration of a single die having a surfacearea that is larger than an image capture device FOV, where the die isproperly aligned relative to the FOV because the die's horizontal andvertical sides are substantially parallel to FOV horizontal and verticalaxes X₁ and Y₁, respectively.

FIG. 2I is a schematic illustration of a single die such as that shownin FIG. 2H, for which die side misalignment relative to FOV horizontaland vertical axes X₁ and Y₁ results in portions of the die remainingoutside of the image capture device FOV.

FIG. 3A is a schematic illustration showing portions of a wafer and/orfilm frame handling system providing a single porous wafer tablestructure for handling both wafers and film frames, and furtherproviding rotational misalignment correction, non-planarity remediation,and/or lateral displacement prevention in accordance with an embodimentof the present disclosure.

FIG. 3B is a schematic illustration showing portions of a wafer and/orfilm frame handling system providing a single porous wafer tablestructure for handling both wafers and film frames, and furtherproviding rotational misalignment correction, non-planarity remediation,and/or lateral displacement prevention in accordance with an embodimentof the present disclosure.

FIG. 4A is a perspective view of a wafer table base tray that includes anon-porous material, such as a ceramic based non-porous material, inaccordance with an embodiment of the present disclosure.

FIG. 4B is a perspective cross sectional view of the base tray of FIG.4A, taken through a line A-A′.

FIG. 5A is a perspective view of the base tray of FIG. 4A into which amoldable, formable, conformable or flowable porous material, such as aceramic based porous material, has been disposed.

FIG. 5B is a perspective cross sectional view of the base tray carryingthe moldable, formable, conformable, or flowable porous ceramic basedmaterial corresponding to FIG. 5A, taken through a line B-B′.

FIG. 5C is a cross sectional view of a post-planarization process vacuumchuck structure corresponding to the base tray carrying hardened porousceramic material corresponding to FIGS. 5A and 5B.

FIG. 5D is a cross sectional view of a vacuum chuck structure producedor manufactured in accordance with an embodiment of the presentdisclosure, which corresponds to FIG. 5C, and which carries a wafer orfilm frame upon a planar vacuum chuck surface.

FIG. 5E is a perspective view of a representative first wafer having afirst standard diameter (e.g., 8 inches) disposed upon a vacuum chuckstructure in accordance with an embodiment of the present disclosure.

FIG. 5F is a perspective view of a representative second wafer having asecond standard diameter (e.g., 12 inches) disposed upon a vacuum chuckstructure in accordance with an embodiment of the present disclosure.

FIG. 5G is a perspective view of a representative third wafer having athird standard diameter (e.g., 16 inches) disposed upon a vacuum chuckstructure in accordance with an embodiment of the present disclosure.

FIG. 6A is a perspective view of a ceramic based vacuum chuck base trayin accordance with another embodiment of the present disclosure, whichincludes a set of ejector pin guide members.

FIG. 6B is a cross-sectional view of the ceramic based vacuum chuck basetray of FIG. 6A, taken thorough a line C-C′.

FIG. 7A is a perspective view of the base tray of FIGS. 4A and 4B, intowhich a moldable, formable, conformable, or flowable porous ceramicbased material has been disposed.

FIG. 7B is a perspective cross sectional view of the base tray carryingthe moldable, formable, or flowable porous ceramic based materialcorresponding to FIG. 7A, taken through a line D-D′.

FIG. 8 is a flow diagram of a representative process for manufacturing avacuum chuck structure in accordance with an embodiment of the presentdisclosure.

FIG. 9 is a cross sectional view of a vacuum chuck structure inaccordance with an embodiment of the present disclosure, whichillustrates initial volumes of moldable porous ceramic based materialslightly exceeding base tray compartment volumes before completion of aplanarization process.

FIG. 10A is a schematic illustration showing an embodiment of amisalignment inspection system configured for determining an extent ofrotational or angular wafer misalignment relative to a film frame inaccordance with an embodiment of the present disclosure.

FIG. 10B is a schematic illustration showing aspects of determining anextent of rotational or angular wafer misalignment relative to a filmframe by a misalignment inspection system such as that shown in FIG. 10Ain accordance with an embodiment of the present disclosure.

FIG. 10C is a schematic illustration showing an embodiment of amisalignment inspection system configured for determining an extent ofrotational or angular wafer misalignment relative to a film frame inaccordance with another embodiment of the present disclosure.

FIG. 10D is a schematic illustration showing aspects of determining anextent of rotational or angular wafer misalignment relative to a filmframe by a misalignment inspection system such as that shown in FIG. 10Cin accordance with an embodiment of the present disclosure.

FIG. 11 is a schematic illustration of a set of end effectors thatincludes at least one end effector which carries a first handlingsubsystem registration element.

FIG. 12A is a schematic illustration showing aspects of a representativemultifunction handling apparatus configured as each of a rotationcompensation apparatus, a flattening apparatus, and a confinementapparatus in a combined, integrated, or unified manner for performingwafer and film frame handling operations in accordance with anembodiment of the present disclosure.

FIG. 12B is a schematic illustration showing portions of a capture armin accordance with an embodiment of the present disclosure.

FIG. 12C is a schematic illustration showing portions of a capturepositioning assembly in accordance with an embodiment of the presentdisclosure, and a representative first positioning of a plurality ofcapture arms at a first position corresponding to a first film framediameter or cross sectional area.

FIG. 12D is a schematic illustration showing portions of the capturepositioning assembly, and a representative second positioning of theplurality of capture arms at a second position corresponding to a secondfilm frame diameter or cross sectional area, which is smaller than thefirst film frame diameter or cross sectional area.

FIG. 13A is a schematic illustration of a film frame carried by amultifunction handling apparatus in accordance with an embodiment of thepresent disclosure.

FIG. 13B is a schematic illustration showing portions of themultifunction handling apparatus rotated about a pick and place z axisZ_(p) to compensate for a first angular misalignment of a first waferrelative to a film frame.

FIG. 13C is a schematic illustration showing portions of themultifunction handling apparatus rotated about the pick and place z axisZ_(pp) to compensate for a second angular misalignment of a second waferrelative to a film frame.

FIGS. 14A-14B are schematic illustrations of multifunction handlingapparatus positioning of capture arm tip elements over portions of awafer to facilitate secure capture of the wafer upon a wafer tablesurface in accordance with an embodiment of the present disclosure.

FIG. 15A is a schematic illustration of a representative wafer that isheld uniformly upon a wafer table surface by way of natural suctionforce and a vacuum force applied to the underside of the wafer.

FIG. 15B is a schematic illustration of the wafer of FIG. 15A followingvacuum force cessation, and the creation of an air cushion between thewafer and the wafer table surface following application of an air puffto the underside of the wafer.

FIG. 15C is a schematic illustration of wafer displacement relative tothe wafer table surface as a result of the air cushion shown in FIG.15B.

FIGS. 15D-15E are schematic illustrations of multifunction handlingapparatus positioning of capture arms and capture arm tip elementsrelative to a wafer in a manner that limits or constrains lateral waferdisplacement along a wafer table surface in accordance with anembodiment of the present disclosure.

FIG. 16 is a flow diagram of a representative process for limiting,controlling, or preventing lateral wafer displacement along a wafertable surface in accordance with an embodiment of the presentdisclosure.

FIG. 17 is a flow diagram of a representative wafer handling process inaccordance with an embodiment of the present disclosure.

FIG. 18 is a flow diagram of a representative film frame handlingprocess in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

In the present disclosure, depiction of a given element or considerationor use of a particular element number in a particular FIG. or areference thereto in corresponding descriptive material can encompassthe same, an equivalent, or an analogous element or element numberidentified in another FIG. or descriptive material associated therewith.The use of “I” in a FIG. or associated text is understood to mean“and/or” unless otherwise indicated. The recitation of a particularnumerical value or value range herein is understood to include or be arecitation of an approximate numerical value or value range.

As used herein, the term “set” corresponds to or is defined as anon-empty finite organization of elements that mathematically exhibits acardinality of at least 1 (i.e., a set as defined herein can correspondto a unit, singlet, or single element set, or a multiple element set),in accordance with known mathematical definitions (for instance, in amanner corresponding to that described in An Introduction toMathematical Reasoning: Numbers, Sets, and Functions, “Chapter 11:Properties of Finite Sets” (e.g., as indicated on p. 140), by Peter J.Eccles, Cambridge University Press (1998)). In general, an element of aset can include or be a system, an apparatus, a device, a structure, anobject, a process, a physical parameter, or a value depending upon thetype of set under consideration.

For purpose of brevity and to aid understanding, the term the term“wafer” as used herein can encompass whole wafers, partial wafers, orother types of whole or partial objects or components (e.g., solarcells) having one or more planar surface areas upon which a set ofoptical inspection processes and/or other processing operations aredesired or required. The term “film frame” in the description thatfollows generally refers to a support member or frame configured forcarrying or supporting a wafer, a thinned or backlapped wafer, or a sawnwafer, for instance, by way of a thin layer or film of material that isdisposed or stretched across a film frame surface area, and to which awafer is mounted or adhered, in a manner understood by one of ordinaryskill in the relevant art. Additionally, the term “wafer table” as usedherein includes an apparatus for holding a wafer or a film frame duringa wafer inspection process or a film frame inspection process,respectively, where the term “wafer table” will be understood by one ofordinary skill in the relevant art to be equivalent, substantiallyequivalent, or analogous to a wafer chuck, a vacuum table, or a vacuumchuck. The term “non-porous material” as used herein is intended to meana material that is at least substantially or essentially impermeable tothe flow or transfer of a fluid such as air or a liquid therethrough,and which is correspondingly at least substantially or essentiallyimpermeable with respect to the communication or transfer of a vacuumforce therethrough (e.g., relative to a given thickness or depth of thenon-porous material, such as a depth greater than approximately 0.50-1.0mm). Analogously, the term “porous material” is intended to mean amaterial that is at least moderately/substantially or essentiallypermeable to the flow or transfer of a fluid such as air or a liquidtherethrough, and which is correspondingly at leastmoderately/substantially or essentially permeable with respect to thecommunication or transfer of a vacuum force therethrough (e.g., relativeto a given thickness or depth of the porous material, such as a depthgreater than approximately 0.50-1.0 mm). Finally, the terms “ceramicbased” and “ceramic based material” in the context of the presentdisclosure are intended to mean a material that is entirely orsubstantially ceramic in its material structure and properties.

Embodiments in accordance with the present disclosure are directed tosystems and processes for handling wafers and film frames, which provide(a) a single or unified porous wafer table configured for handling bothwafers and film frames in a manner that facilitates or enables accurate,high throughput inspection processes; and (b) subsystems, devices, orelements configured for automatically (i) remediating insufficientvacuum retention of wafers upon the wafer table due to wafer warpage ornon-planarity; (ii) preventing lateral displacement of wafers due tovacuum force cessation and/or air purge application; and/or (iii)correcting or compensating for rotational misalignment of wafers carriedby film frames. Several embodiments in accordance with the presentdisclosure are directed to systems and processes that can provide eachof the foregoing.

While multiple embodiments in accordance with the present disclosure aredirected to wafer and film frame inspection systems (e.g., opticalinspection systems), several embodiments in accordance with the presentdisclosure can additionally or alternatively be configured forsupporting or performing other types of wafer and/or film frame frontend or back end processing operations, such as test operations. Aspectsof representative embodiments in accordance with the present disclosureare described in detail hereafter with primary emphasis on inspectionsystems for purpose of brevity and to aid understanding.

By way of a single or unified wafer table configured for handling bothwafers and film frames, embodiments in accordance with the presentdisclosure eliminate the need for or exclude a wafer table conversionkit, thus eliminating production downtime due to wafer-to-film frame andfilm frame-to-wafer conversion kit changeover and calibrationoperations, thereby enhancing average inspection process throughput. Asingle or unified wafer table in accordance with an embodiment of thepresent disclosure facilitates or enables high accuracy inspectionoperations by providing a wafer table surface having a high or very highdegree of planarity that maintains wafer die surfaces in a commoninspection plane with minimal or negligible deviation therefrom along adirection parallel to a normal axis of the highly planar wafer tablesurface.

Additionally, embodiments in accordance with the present disclosure caneliminate the need for manual intervention that in the past was neededto address (a) lack of wafer retention upon a wafer table surface due towafer warpage or non-planarity, and (b) unpredictable lateral motion ofa wafer along a wafer table surface following the interruption orcessation of a vacuum force that retained the wafer to the wafer tablesurface and/or the momentary application of a puff of positive air tothe underside of the wafer by the wafer table to remove any residualvacuum suction. Furthermore, embodiments in accordance with the presentdisclosure can eliminate the need for manual intervention ormechanically complex and undesirably expensive rotatable wafer tableassemblies which in the past were required to correct rotationalmisalignment of a wafer relative to a film frame on which the waferresides (e.g., when wafer misalignment relative to the film frameexceeded a given threshold misalignment magnitude).

Aspects of a Representative System Configuration and System Elements

FIG. 3A is a block diagram of a system 200 for handing wafers 10 andfilm frames 30 in accordance with an embodiment of the presentdisclosure, which includes a wafer table assembly 610 having a single orunified wafer table 620 which provides a high or very high planaritysurface 622 configured for handling both wafers and film frames duringinspection processes (e.g., wafer inspection processes and film frameinspection processes, respectively) by an inspection system 600. Thesystem 200 further includes a first handling subsystem 250 and a secondhandling subsystem 300 which are configured for (a) conveying wafers 10and film frames 30 to and from the inspection system 600, and (b)providing wafer-to-film frame rotational misalignment correction andwafer non-planarity remediation as part of pre-inspection handlingoperations, and lateral displacement prevention as part ofpost-inspection handling operations, as further detailed below.

Depending upon whether wafers 10 or film frames 30 are being inspectedat a given time, the system 200 includes a wafer source 210 such as awafer cassette, or a film frame source 230 such as a film framecassette, respectively. Similarly, if wafers 10 are being inspected, thesystem 200 includes a wafer destination 220 such as a wafer cassette (ora portion of a processing station); and if film frames 30 are beinginspected, the system 200 includes a film frame destination 240, whichcan be a film frame cassette (or a portion of a processing system). Awafer source 210 and a wafer destination 220 can correspond to or be anidentical location or structure (e.g., the same wafer cassette).Similarly, a film frame source 220 and a film frame destination 240 cancorrespond to or be an identical location or structure (e.g., the samefilm frame cassette).

The system 200 also includes a wafer pre-alignment or alignment station400 configured for establishing an initial or pre-inspection alignmentof wafers 10 such that wafers 10 are properly aligned relative to theinspection system 600; a rotational misalignment inspection system 500configured for receiving, retrieving, determining, or measuring arotational misalignment direction and a rotational misalignmentmagnitude (e.g., which can be indicated by a rotational misalignmentangle) corresponding to wafers 10 mounted upon film frames 30; and acontrol unit 1000 configured for managing or controlling aspects ofsystem operation (e.g., by way of the execution of stored programinstructions), as further detailed below. The control unit 1000 caninclude or be a computer system or computing device, which includes aprocessing unit (e.g., a microprocessor or microcontroller), a memory(e.g., which includes fixed and/or removable random access memory (RAM)and read-only memory (ROM)), communication resources (e.g., standardsignal transfer and/or network interfaces), data storage resources(e.g., a hard disk drive, an optical disk drive, or the like), and adisplay device (e.g., a flat panel display screen).

In multiple embodiments, the system 200 additionally includes a supportstructure, base, underframe, or undercarriage 202 that is coupled to orconfigured for supporting or carrying at least the second handlingsubsystem 300 such that the second handling subsystem 300 canoperatively interface with the first handling subsystem 250 and theprocessing system 600 to facilitate wafer or film frame handlingoperations. In some embodiments, the support structure 202 supports orcarries each of the first handling subsystem 250, the second handlingsubsystem 300, the wafer alignment station 400, the misalignmentinspection system 500, and the inspection system 600.

FIG. 3B is a block diagram of a system 200 for handing wafers 10 andfilm frames 30 which provides a single or unified wafer table 620configured for handling both wafers and film frames during inspection byan inspection system 600, and which further provides a first handlingsubsystem 250 and a second handling subsystem 300 in accordance withanother embodiment of the present disclosure. In this embodiment, awafer source 210 and a wafer destination 230 are identical, e.g., thesame wafer cassette; and a film frame source 220 and a film framedestination 240 are identical, e.g., the same film frame cassette. Suchan embodiment can provide a smaller or significantly reduced spatialfootprint, resulting in a compact, space efficient system 200. In arepresentative embodiment, the inspection system 600 is configured forperforming 2D and/or 3D optical inspection operations upon wafers 10 andfilm frames 30. An optical inspection system 600 can include a number ofillumination sources, image capture devices (e.g., cameras) configuredfor capturing images and generating image data sets correspondingthereto, and optical elements configured for some or each of directingillumination toward wafers 10, directing illumination reflected fromwafer surfaces toward particular image capture devices, reflecting oroptically affecting (e.g., filtering, focusing, or collimating)illumination incident upon and/or reflected from wafer surfaces, in amanner understood by one of ordinary skill in the relevant art. Theoptical inspection system 600 also includes or is configured forcommunication with a processing unit and a memory for analyzing imagedata sets by way of the execution of stored program instructions, andgenerating inspection results.

As previously indicated, the inspection system 600 can include oralternatively be another type of processing system at which one or moreof the following are desired or required: (a) a wafer table 620configured for handling wafers 10 and/or film frames 30, which providesa wafer table surface 622 having very high planarity for collectivelymaintaining wafer die 12 in a common plane during processing operations,with negligible planar deviation therefrom; (b) correct alignment ofwafers 10 exhibiting an amount of misalignment relative to film frames30 that exceeds a misalignment threshold magnitude (e.g., a maximumwafer-to-film frame rotational misalignment tolerance, which should ormust be satisfied for maximum throughput inspection, such as furtherdetailed below with reference to FIGS. 10A-10D); (c) uniform secureretention of wafers 10 or film frames 30, including non-planar or warpedwafers 10, by the wafer table 620; and/or (d) prevention of unintended,unpredictable, or uncontrolled lateral wafer displacement along thewafer table surface 622.

With further reference to FIG. 3C, the wafer table 620 carried by thewafer table assembly 610 provides a highly planar external or exposedwafer table surface 622 upon which wafers 10 as well as film frames 30can be positioned and securely held or retained, such that wafer die 12are collectively maintained in a common inspection plane with minimum ornegligible planar deviation therefrom, along a direction parallel to anormal axis Z_(wt) of the highly planar wafer table surface 622 definednormal to a midpoint, center, centroid, or approximate midpoint, center,or centroid of the wafer table surface 622. The wafer table assembly 610is configured for selectively and controllably displacing the wafertable 620, and hence any wafer 10 or film frame 30 carried or securelyheld thereby, along two transverse spatial axes corresponding to ordefining a plane, for instance, wafer table x and y axes X_(vt) andY_(vt), respectively, each of which is also transverse to axis Z_(vt).

The wafer table 620 is configured for selectively and securely holdingor retaining wafers 10 or film frames 30 upon or against the wafer tablesurface 622 by way of (a) an inherent or natural suction force thatexists due to a pressure differential between atmospheric pressureacting upon the wafer's top, upper, or exposed surface and the wafer'sbottom or underside, in combination with (b) the selectively controlledapplication of vacuum force or negative pressure to the underside of thewafer 10. The wafer table 620 can further be configured for applying ordelivering a brief/momentary, e.g., approximately 0.50 second, or0.25-0.75 second, spurt of positive air pressure, e.g., an air purge orair puff, to an interface between the wafer table surface 622 and theunderside of wafers 10 or film frames 30 to facilitate the release ofvacuum suction acting on the wafers 10 or film frames 30 from the wafertable surface 622 following the interruption or cessation of an appliedvacuum force.

In various embodiments, the wafer table assembly 610 includes a set ofejector pins 612 that can be selectively and controllably displaced in aperpendicular or vertical direction relative to the wafer table surface622, parallel to or along the wafer table z axis Z_(wt) for verticallydisplacing wafers 10 or film frames 30 relative to the wafer tablesurface 622. In multiple embodiments, the wafer table 620 includes asingle set of ejector pins 612 (e.g., three ejector pins) configured forhandling wafers 10 of multiple standard sizes, such as 8, 12, and 16inch wafers 10. The wafer table 620 need not include, and can omit orexclude, additional sets of ejector pins 612 (e.g., additional sets ofthree ejector pins), due to the positioning of the single set of ejectorpins 612 upon the wafer table 620 (e.g., positioned to carry 8-inchwafers somewhat near, generally near, near, or proximate to theirperiphery) and the manner in which wafers and film frames are handled inaccordance with embodiments of the present disclosure. As furtherdetailed below, in several embodiments, while ejector pins 612 can beused in association with the transfer of wafers 10 to and from the wafertable 620, the transfer of film frames 30 to and/or from the wafer table620 need not involve, and can omit or entirely exclude, the use ofejector pins 612.

In multiple embodiments, the wafer table 620 has a structure that isidentical, essentially identical, substantially identical, or analogousto a wafer table structure described hereafter with reference to FIGS.4A-FIG. 9.

Aspects of a Representative Unified Wafer Table Structure for Wafer andFilm Frame Handling

In embodiments in accordance with the present disclosure, a wafer tablestructure can include a base tray (or base receptacle, frame, form,repository, or reservoir structure) having a number of ridges (which caninclude or be protrusions, ridges, raised strips, partitions,corrugations, creases, or folds) formed integrally from or attached toan interior or base surface of the wafer table structure (e.g., thebottom of base tray). In various embodiments, the base tray can includesat least one type of non-porous material, such as a ceramic basedmaterial. The base tray is intended to be gas or fluid (e.g., air)impermeable, or essentially gas or fluid impermeable, in response toapplication of vacuum force(s). That is, the non-porous material isintended to be impervious or essentially impervious to the passage ofgas, fluid, or vacuum force(s) therethrough in response to appliedvacuum force(s). The non-porous material is further intended to beeasily or readily machinable, grindable, or polishable by ordinarytechniques and equipment, such as conventional polishing wheels. Inmultiple embodiments, the non-porous material can include or beporcelain.

The ridges define, delineate, divide, or separate the base tray intomultiple compartments, chambers, cell structures, open regions, orrecesses into which at least one type of moldable, formable,conformable, or flowable porous material can be introduced, provided,deposited, or poured and cured, solidified, or hardened. The porousmaterial can further be securely bonded (e.g., chemically bonded, suchas in association with a hardening, solidification, or curing process)or adhered to the base tray compartments, such that the hardened porousmaterial is securely retained within or joined to the compartments.Additionally or alternatively, the ridges can be shaped in such a waysuch that the porous material when hardened or cured within thecompartments is secured or retained therein by the structure of theridges. The ridges can be structured to include curved and/oroverhanging portions, or take other suitable shapes, as desirable orrequired.

The porous material in the compartments is intended to permit thepassage of gas or fluid (e.g., air) in response to the application ofvacuum force(s) thereto, such that gas, fluid, or vacuum force(s) can becommunicated or transmitted therethrough (e.g., after it has been curedor hardened, and vacuum force(s) are applied thereto). Furthermore, theporous material is intended to be easily or readily machinable,grindable, or polishable by ordinary techniques and equipment, such asconventional polishing wheels.

The choice of non-porous base tray material(s), and/or porousmaterial(s) for introduction into base tray compartments, for the wafertable structure depends upon the desired or required characteristics ofthe wafer table structure in relation to the application or process thatis to be carried out on a wafer 10 or film frame 30 residing thereon.For instance, optical inspection of small or ultra-small die 12 on largediameter sawn wafers 10 carried by film frames 30 requires that thewafer table structure provide a wafer table surface having a very highor ultra-high degree of planarity. Moreover, the choice of non-porousbase tray material(s) and/or porous compartment material(s) can dependupon the chemical, electrical/magnetic, thermal, or acousticrequirements that the wafer table structure should meet in view of theexpected or intended types of wafer or film frame processing conditionsto which the wafer table structure will be exposed.

In various embodiments, the non-porous base tray material(s) and theporous compartment material(s) are selected based on materialcharacteristic(s) or quality(ies) that will facilitate or enable thegrinding or polishing across multiple exposed surfaces of at least twodistinguishable or different materials by a single grinding or polishingapparatus (e.g., substantially or essentially simultaneously). Moreparticularly, exposed surfaces of the two (or more) distinguishable ordifferent non-porous and porous materials can be simultaneouslymachined, grinded, or polished in the same or an identical manner, suchas by way of a single, common, or shared process that involves standardmachining, grinding, or polishing equipment operating or operated inaccordance with standard machining, grinding, or polishing techniques.Such machining, grinding, or polishing of each of the non-porous andporous materials results in low, minimal, or negligible damage tomachining, grinding, or polishing elements, devices, or tools such aspolishing heads. Furthermore, in a number of embodiments, the non-porousbase tray material(s) and porous compartment material(s) are selectedsuch that a rate at which the non-porous base tray material(s) areaffected (e.g., planarized) by such machining, grinding, or polishingand the rate at which the porous compartment material(s) is/are affected(e.g., planarized) by such machining, grinding, or polishing aresubstantially or essentially identical.

For purpose of brevity and ease of understanding, in the representativeembodiments of wafer table structures described below, the non-porousbase tray material includes or is a non-porous ceramic based material,and the porous compartment material includes or is a porous ceramicbased material. One of ordinary skill in the relevant art willunderstand that a wafer table structure in accordance with an embodimentof the present disclosure is not limited to the material types providedin relation to the representative embodiments described below.

When the creation of a very flat, highly planar, or ultra-planar wafertable surface is desired or required, the porous material can include amoldable porous based ceramic material and/or other chemical compoundwhich is suitable for forming, fabricating, or manufacturing a porouswafer table, wafer chuck, vacuum table, or vacuum chuck in accordancewith standard/conventional processing techniques, processing sequencesand processing parameters (e.g., hardening temperatures or temperatureranges, and corresponding hardening times or time intervals), in amanner understood by one of ordinary skill in the relevant art. Inmultiple embodiments, the porous material can include or be acommercially available material provided by CoorsTek (CoorsTek Inc.,Hillsboro, Oreg. USA, 503-693-2193). Such a porous material can includeor be one or more types of ceramic based materials, such as AluminumOxide (Al2O3) and Silicon Carbide (SiC), and can exhibit apost-hardened/post-cured pore size between approximately 5-100 μm (e.g.,about 5, 10, 30, or 70 μm), and a porosity ranging between approximately20-80% (e.g., about 30-60%). The pore sizes of the porous compartmentmaterial(s) can be selected based upon application requirements, such asan intended or desired level of vacuum force suitable for an applicationunder consideration (e.g., the inspection of thin or very thin wafers 10on film frames 30), as will be understood by one of ordinary skill inthe art. Exposed, upper, or outer surfaces corresponding to portions ofthe ceramic base tray (e.g., the set of ridges, and possibly an outerbase tray border) and hardened moldable porous ceramic material carriedby base tray compartments can be machined (e.g., by way of a unified orsingle machining or polishing process) to provide a common wafer tablesurface exhibiting a very high or ultra-high degree of planarity orplanar uniformity, which is suitable for securely retaining wafers orfilm frames in a manner that effectively disposes or maintains the waferdie surfaces along or within a common plane (perpendicular to the normalaxis of the wafer table surface) with minimal or negligible deviationtherefrom, e.g., during inspection.

FIG. 4A is a perspective view of a ceramic based base tray 100, and FIG.4B is a perspective cross sectional view of the base tray of FIG. 4A,taken through line A-A′, in accordance with an embodiment of thedisclosure. As indicated above, in various embodiments the ceramic basedbase tray 100 is non-porous or, essentially non-porous, and hence isimpervious or essentially impervious with respect to gas, fluid, orvacuum force transfer therethrough in response to applied vacuumforce(s). That is, the ceramic based base tray 100 is typically intendedto serve as a strong, very strong, or effectively impenetrable barrierrelative to the communication or transfer of gas, fluid, or vacuumforce(s) therethrough.

In an embodiment, the base tray 100 has a shape that defines a center orcentroid 104, relative to or surrounding which a vacuum opening 20 canbe disposed; a planar or transverse spatial extent or area A_(T); anouter periphery or border 106; a plurality of inner bottom surfaces 110a-c, which can include a number of vacuum openings 20 disposed therein;and one or more ridges 120 a-b disposed between the base tray's centerand its outer border 106 (e.g., in an annular or concentricarrangement). As further detailed below, in various embodiments theridges 120 a-b, as well as the base tray's outer border 106, are sized,shaped, and/or dimensioned in a manner correlated with or correspondingto standard wafer and/or film frame sizes, shapes, and/or dimensions(e.g., 8-inch, 12-inch, and 16-inch wafers, and one or more film framesizes corresponding to such wafer sizes). The base tray 100 furtherincludes at least one underside surface 150, significant portions or theentirety of which in a number of embodiments are disposed orsubstantially disposed in a single base tray underside plane.

In several embodiments, a vertical base tray axis Z_(T) can be definedperpendicular or substantially perpendicular to the base tray'sunderside surface 150 and the base tray's inner bottom surfaces 110 a-c,and extending through the base tray's center or centroid 104. As will beunderstood by one of ordinary skill in the relevant art, the verticalbase tray axis Z_(T) is defined perpendicular to an intended wafer tableplanar surface upon or against which a wafer or film frame can besecurely held or retained. In FIGS. 4A and 4B, Z_(T) can beperpendicular to the line A-A′, which bisects each vacuum opening 20.

Each ridge 120 a-b borders inner bottom surfaces 110 a-c of the basetray 100, and each ridge 120 a-b delineates, separates, or partitionsportions of different base tray inner bottom surfaces 110 a-c from eachother to define a set of base tray compartments or receptacles 130 a-bthat can receive or carry the aforementioned moldable, formable,conformable, or flowable porous material. More particularly, in theembodiment shown in FIG. 4A, a first ridge 120 a extends above andsurrounds (e.g., concentrically surrounds) a first inner bottom surface110 a of the base tray 100. A contiguous or generally contiguousstructural recess defined by the first ridge 120 a surrounding orencircling the first inner bottom surface 110 a thereby defines a firstbase tray compartment or receptacle 130 a, which has as its bottomsurface the first inner bottom surface 110 a. In an analogous manner,the first ridge 120 a and the second ridge 120 b extend above a secondinner bottom surface 110 b of the base tray 100. The second ridge 120 bencloses the first ridge 120 a (e.g., the first and second ridges 120a-b are concentric relative to each other), such that the first andsecond ridges 120 a-b define a second contiguous or generally contiguousbase tray compartment or receptacle 130 b having as its bottom surfacethe second inner bottom surface 110 b. Also analogously, the base tray'souter border 106 encloses the second ridge 120 b (e.g., the second ridge120 b and the outer border 106 are concentric relative to each other),such that they define a third contiguous or generally contiguous basetray compartment or receptacle 130 c having as its bottom surface thethird inner bottom base tray surface 110 c. Any given ridge 120 has atransverse ridge width, for instance, approximately 1-4 mm (e.g.,approximately 3 mm); and a corresponding ridge depth, for instance,approximately 3-6 mm (e.g., approximately 4 mm) which defines the depthof a compartment or receptacle 130. As further described below, invarious embodiments, any given base tray compartment or receptacle 130a-c has a spatial extent, planar surface area, or diameter that iscorrelated with or corresponds to the spatial extent, planar surfacearea, or diameter of standard wafer and/or film frame sizes, shapes,and/or dimensions.

Similar or analogous considerations to the foregoing apply to thedefinition of additional or other types of base tray compartments orreceptacles 130 in alternate embodiments, including embodiments having asingle ridge 120; embodiments having more than two ridges 120 a-b;and/or embodiments in which portions of one or more ridges 120 do notfully enclose one another, or are not annular/concentric with respect toone or more other ridges 120 (e.g., when portions of a particular ridge120 are transversely, radially, or otherwise disposed with respect toanother ridge 120). The manner in which ridges 120 exhibiting variousshapes, sizes, dimensions, and/or segments (e.g., a ridge 120 caninclude multiple distinct or separate segments or sections disposed withrespect to an elliptical, circular, or other type of geometric outlineor pattern) can define different types of base tray compartments orreceptacles 130 will be readily understood by one of ordinary skill inthe relevant art.

In addition to the foregoing, the base tray's outer border 106 as wellas each ridge 120 a-b respectively includes an exposed outer borderupper surface 108 and an exposed ridge upper surface 122 a-b,corresponding to an upper surface or upper side of the base tray 100that, relative to the base tray's underside surface 150, is intended tobe closest to a wafer 10 or film frame 30 carried by a wafer tableplanar surface. In multiple embodiments, a vertical distance (e.g.,parallel to the base tray's central transverse axis Z_(T)) between thebase tray's outer border upper surface 108 and the base tray's innerbottom surfaces 110 a-c, as well as between each ridge upper surface 122a-b and the base tray's inner bottom surfaces 110 a-c, defines a basetray compartment depth D_(TC). A vertical distance between the basetray's outer border upper surface 108 and the base tray's undersidesurface 150 defines an overall base tray thickness. T_(OT). Finally, avertical distance along which a vacuum opening 20 extends can define avacuum passage depth D_(V), which is equal to the difference betweenT_(OT) and D_(TC).

FIG. 5A is a perspective view of the base tray 100 of FIG. 4A into whicha moldable, formable, conformable, or flowable porous material has beenintroduced, disposed, or provided to effectively provide the basis for,facilitate or effectuate the formation of, or form a wafer tablestructure 5 in accordance with an embodiment of the present disclosure.FIG. 5B is a perspective cross sectional view of the base tray 100carrying the porous material corresponding to FIG. 5A, taken through theline B-B′. FIG. 5C is a cross sectional view of the base tray 100carrying the porous material corresponding to FIGS. 5A and 5B.

In FIGS. 5A and 5B, the porous material can be considered to be residentwithin the base tray compartments 130 a-c in a pre-hardened/pre-set orpost-hardened/post-set state, depending upon a stage of wafer tablestructure fabrication under consideration. Furthermore, if considered ina post-hardened/post-set state, the porous material and the non-porousor vacuum impervious ceramic based base tray 100 can be considered in apre-planarized/pre-machined or post planarized/post-machined state, onceagain depending upon a wafer table structure fabrication stage underconsideration. Stages of a representative wafer table structurefabrication process in accordance with an embodiment of the presentdisclosure are described in detail below.

In view of FIGS. 5A-5C and relative to the base tray embodiment shown inFIGS. 4A and 4B, following the introduction, placement, deposition, orprovision of the porous material into the base tray compartments 130 a-cand the conformation of the porous material to the internal geometry ofthe base tray compartments 130 a-c, the first base tray compartment 130a is filled by a first volume 140 a of porous material; the second basetray compartment 130 b is filled by a second volume 140 b of porousmaterial; and the third base tray compartment 130 c is filled by a thirdvolume 140 c of porous material. Analogous or similar considerationsapply to other base tray embodiments having different numbers and/orconfigurations of compartments 130. That is, after the porous materialhas been introduced into base tray compartments 130, each of suchcompartments 130 is filled with a given volume 140 of the porousmaterial corresponding to the dimensions or volumetric capacity of anygiven compartment 130 under consideration. An initial volume 140 ofporous material introduced into any given base tray compartment 130should equal or exceed the compartment's volume, such that excess porousmaterial can be machined or polished away in association with aplanarization process, as further detailed below.

After the introduction of the porous material into a compartment 130,portions of any given volume 140 of porous material are exposed to anumber of vacuum openings 20 within the compartment 130. Moreparticularly, within a given volume 140 of porous material, porousmaterial that interfaces with a base tray inner bottom surface 110 areselectively exposed to one or more vacuum openings 20 disposed or formedwithin a corresponding base tray inner bottom surface 110. For instance,as more particularly indicated in the embodiment shown in FIGS. 5B and5C, the first volume 140 a of porous material is exposed to the vacuumopening 20 disposed at the center of the base tray 100 within the firstinner bottom surface 110 a of the first base tray compartment 130 a.Analogously, the second volume 140 b of porous material is exposed tothe vacuum openings 20 disposed within the second inner bottom surface110 b of the second base tray compartment 130 b; and the third volume140 c of porous material is exposed to the vacuum openings 20 disposedwithin the third inner bottom surface 110 c of the third base traycompartment 130 c. Because each volume 140 a-c of porous material isexposed to a corresponding set of vacuum openings 20, vacuum force(s)can be selectively communicated, distributed, or transferred througheach volume 140 a-c of porous material, to the upper surface of theporous material corresponding to the upper surface of the wafer tablestructure 5. Hence, when the wafer table structure 5 carries a wafer 10or film frame 30 of a particular size or shape upon a planar wafer tablesurface, vacuum force(s) can be selectively communicated or transferredto the underside of a wafer 10 or film frame 30 through thecorresponding base tray compartments covered by the wafer 10 or filmframe 30 disposed upon a wafer table planar surface, as furtherelaborated upon below.

As indicated above and further elaborated upon below, after the porousmaterial volumes 140 have been introduced into the base traycompartments 130, each such volume 140 can be hardened, solidified, orcured and bonded (e.g., collectively, in association or simultaneouswith a hardening/bonding process) to an interior bottom surface 110 andassociated side surfaces or sidewalls of one or more ridges 120 thatdefine a compartment 130. Additionally, following a hardening/bondingprocess, exposed upper surfaces of the wafer table structure 5, whichinclude exposed upper surfaces of the volumes 140 of porous material,exposed ridge upper surfaces 122, and the exposed outer border uppersurface 108 can be simultaneously machined, polished, or planarized byway of one or more conventional, technologically simple, inexpensive,and robust machining or polishing techniques or processes using a singlemachining, grinding, or polishing apparatus across two distinguishableor different material surfaces. Furthermore, the use of singlemachining, grinding, or polishing apparatus gives rise to, provides, ordefines a wafer table planar surface that exhibits a very high orultra-high degree of planar uniformity. As a result, die 12 carried by awafer 10 or film frame 30 disposed and securely held or retained uponthe wafer table planar surface are maintained in a common plane in amanner that effectively maintains the upper or exposed die surfaces insaid common plane with minimal or negligible deviation therefrom, evenfor very small die and/or very thin wafers. The upper surfaces of suchdie 12 therefore exhibit minimal or negligible positional deviation outof said common plane, along a direction parallel to a normal axis of thehighly planar wafer table surface (e.g., a wafer table vertical axisZ_(WT) corresponding to, overlapping with, or subsuming the base tray'svertical axis Z_(T)). The ultra-high planarity of the wafer tablesurface provided by multiple embodiments in accordance with presentdisclosure enables the die 12 on wafers 10 or film frames 12 residing onthe wafer surface to sit substantially in/on one single plane (e.g., aninspection plane) to facilitate accurate inspection and/or otherprocessing.

FIG. 5D is a cross sectional view of a wafer table structure 5 producedor manufactured in accordance with an embodiment of the presentdisclosure, which corresponds to FIG. 5C, and which and which carries awafer or film frame upon a planar wafer table surface. The wafer tablestructure 5 provides a wafer table planar surface 190 having a very highor ultra-high degree of planar uniformity, such that die 12 (e.g., verysmall and/or very thin die 12), devices, or material layers carried by awafer 10 or film frame 30 that is securely held or retained upon thewafer table planar surface by way of vacuum force(s) are collectively orcommonly maintained, essentially maintained, or very substantiallymaintained in a wafer or film frame processing plane 192 (e.g., anoptical inspection plane) with minimal or negligible positionaldeviation or displacement away from or out of the wafer or film frameprocessing plane 192 in a direction along a wafer table vertical axisZ_(WT) (or equivalently, in a direction toward or away from the wafertable planar surface 190). In a representative embodiment, exposed orupper surfaces of die 12 having a planar surface area of betweenapproximately 0.25-0.50 mm square or larger and a thickness ofapproximately 25-50 microns or greater can collectively exhibit avertical deviation from the wafer or film frame processing plane 192 ofless than approximately +/−100 μm, or less than approximately 10 to 90μm (e.g., less than approximately +/−20 to 80 μm, or on average lessthan approximately 50 μm). Very small or ultra-small die 12 (e.g.,approximately 0.25-0.55 mm square) and/or very thin or ultra-thin die 12(e.g., approximately 25-75 μm or approximately 50 μm thick) can bemaintained within an inspection plane 192 such that their deviation outof the inspection plane 192 is less than approximately 20-50 μM.

As previously indicated, the maximum transverse dimension or diameter ofa given volume 140 of porous material within a particular base traycompartment 130, as well as the planar spatial extent or surface areaspanned by a ridge 120 that defines or limits the maximum planar spatialextent or surface area of the compartment 130 in which the volume 140 ofporous material resides, is correlated with or corresponds to aparticular standard or expected wafer and/or film frame size, planarspatial extent or surface area, dimension, or diameter. Moreparticularly, in order to securely hold or retain a wafer 10 or filmframe 30 of a given size to the wafer table planar surface 190, vacuumforce is provided or delivered to the wafer 10 or film frame 30 by wayof selectively providing or delivering vacuum force to or through thevacuum opening(s) 20 disposed within or exposed to the compartment 130having a maximum transverse dimension or diameter that most closelymatches the transverse dimension or diameter of the wafer or film framesize currently under consideration, as well as each compartment 130corresponding to a wafer or film frame size that is smaller than that ofthe wafer 10 or film frame 30 currently under consideration. Thus, awafer 10 or film frame 30 of a particular size should entirely cover theupper surface of (a) a volume 140 of porous material having a transversedimension or diameter that most closely matches the size of the wafer 10or film frame 30 under consideration, as well as (b) each volume 140 ofporous ceramic material having a smaller transverse dimension ordiameter. A wafer 10 or film frame 30 should also cover a portion of theridge 120 that most closely matches the size of the wafer 10 or filmframe 30, as well as each ridge 120 having a diameter that is smallerthan the wafer 10 or film frame 30 under consideration.

FIG. 5E is a perspective view of a representative first wafer 10 a ahaving a first standard diameter (e.g., 8 inches) disposed upon a wafertable structure 5 in accordance with an embodiment of the presentdisclosure, such that the first wafer 10 a can be securely retained uponthe wafer table planar surface 190 by way of (a) the first wafer 10 acovering the first volume 140 a of porous material and covering at leasta portion of the transverse width of the first ridge 120 a, but notextending to or overlapping with the second volume 140 b of porousmaterial; and (b) the application or delivery of vacuum force to thefirst wafer 10 a by way of selective or preferential provision of vacuumforce to or through the first compartment's vacuum opening 20, into andthrough the first volume 140 a of porous material, to an underside ofthe first wafer 10 a.

FIG. 5F is a perspective view of a representative second wafer 10 bhaving a second standard diameter (e.g., 12 inches) disposed upon awafer table structure 5 in accordance with an embodiment of the presentdisclosure. The second wafer 10 b can be securely retained upon thewafer table planar surface 190 by way of (a) the second wafer 10 bcovering the first and second volumes 140 a-b of porous material andcovering at least a portion of the transverse width of the second ridge120 b, but not extending to or overlapping with the third volume 140 cof porous material; and (b) the application or delivery of vacuum forceto the second wafer 10 b by way of selective or preferential provisionof vacuum force to or through the first compartment's vacuum opening 20and the second compartment's vacuum openings 20, into and through thefirst and second volumes 140 a-b of porous material, to an underside ofthe second wafer 10 b.

FIG. 5G is a perspective view of a representative third wafer 10 chaving a third standard diameter (e.g., 16 inches) disposed upon a wafertable structure 5 in accordance with an embodiment of the presentdisclosure. The third wafer 10 c can be securely retained upon the wafertable planar surface 190 by way of (a) the third wafer 10 c covering thefirst, second, and third volumes 140 a-c of porous material and coveringa portion of the transverse width of the base tray's outer border 106;and (b) the application or delivery of vacuum force to the third wafer10 c by way of selective or preferential provision of vacuum force to orthrough the first compartment's vacuum opening 20, the secondcompartment's vacuum openings 20, and the third compartment's vacuumopenings 20, into and through the first, second, and third volumes 140a-c of porous material, to an underside of the third wafer 10 c.

In addition to the foregoing, in a number of embodiments a ceramic basedbase tray 100 can include or be formed to accommodate or provide one ormore additional types of structural features or elements. Particularrepresentative non-limiting embodiments of such ceramic based trays 102are described in detail hereafter.

FIG. 6A is a perspective view of a ceramic based wafer table base tray100 in accordance with another embodiment of the present disclosure,which includes a set of ejector pin guide members 160. FIG. 6B is across-sectional view of the ceramic based wafer table base tray of FIG.6A, taken thorough a line C-C′. In such an embodiment, the base tray 100can have a general or overall structure that is analogous orsubstantially identical to that described above. However, the firstridge 110 a includes a number of ejector pin guide structures, elements,or members 160 a-c (e.g., three in various embodiments, which issufficient for enabling three ejector pins to handle each of 8 inch, 12inch, and 16 inch wafers corresponding to such wafer sizes). Eachejector pin guide member 106 a-c is shaped and configured for providingan opening 162 corresponding to or defining a passage or pathway throughwhich an ejector pin can travel. In multiple embodiments, any givenejector pin guide member 160 a-c can be formed as an integral portion orextension of the first ridge 110 a, such that the ejector pin guidemember 160 a-c protrudes into a portion of the first compartment 120 a.Moreover, ejector pin guide members 160 a-c are dimensioned and/orconstructed in such a manner such that essentially no, negligible, orminimal vacuum loss occurs through the ejector pin guide members 160 a-cduring wafer table structure use (e.g., during ejector pin elevation andlowering). In several embodiments, ejector pin guide members 160 a-c canbe strategically disposed such that a single set of ejector pins 164 canhandle each wafer and film frame size that the wafer table structure 5is designed to handle. One of ordinary skill in the relevant art willunderstand that ejector pin guide members 160 a-c could alternatively oradditionally be formed separate from the first ridge 110 a, or as aportion of another ridge 110 (e.g., the second ridge 110 b). FIG. 7A isa perspective view of the base tray 100 of FIGS. 6A and 6B into which amoldable, formable, conformable, or flowable porous material has beenintroduced, provided, or disposed. FIG. 7B is a perspective crosssectional view of the base tray 100 carrying the moldable porousmaterial corresponding to FIG. 7A, taken through a line D-D′. It shouldbe noted that when the moldable porous material is introduced into thebase tray 100, the opening 162 within and through each ejector pin guidemember 160 a-c should be sealed or blocked, such that porous material isexcluded from the opening 162 and the passage through the ejector pinguide member 160 a-c corresponding thereto in order to ensure thattravel of an ejector pin 164 a-c through the passage and the opening 162is not impeded by hardened moldable porous material during ejector pinactuation involving the lowering or raising of wafers or film framesrelative to the wafer table planar surface 190.

In some embodiments, the base tray 100 can carry, include, orincorporate a number of heating and/or cooling elements. For instance,heating elements can include resistive heating elements. Coolingelements can include tubes, channels, or passages which are configuredfor carrying a cooling substance or fluid (e.g., a chilled gas, or aliquid); or a thermoelectric cooling device. Heating and/or coolingelements can be enclosed or encapsulated within the non-porous ceramicbased base tray material (e.g., integrally formed within one or moreportions of the base tray 100). Alternatively, heating and/or coolingelements can reside external to the non-porous ceramic based base traymaterial, enclosed or encapsulated within portions of the porousmaterial that occupies the base tray receptacles 130. In addition or asan alternative to the foregoing, the non-porous ceramic based base tray100 and/or the porous material that occupies the base tray receptacles130 can carry, include, or incorporate additional or other types ofelements, such as electrodes, temperature sensing elements (e.g.,thermocouples), other types of sensing elements (e.g., accelerometers,vibration sensors, or optical sensors), and/or other types of sensingelements configured for sensing surrounding/environmental conditionswithin and/or external to portions of the wafer table structure 5.

FIG. 8 is a flow diagram of a representative process 170 formanufacturing a wafer table structure 5 in accordance with an embodimentof the present disclosure. In an embodiment, a wafer table manufacturingprocess 170 includes a first process portion 172 involving providing anon-porous ceramic based wafer table base tray 100 having a plurality ofcompartments 130 therein; a second process portion 174 involvingproviding a moldable porous material; and a third process portion 176comprising introducing the moldable porous material into the pluralityof compartments 130 and filling the volumetric geometry of eachcompartment 130 within the plurality of compartments 130 with themoldable porous material, such that the moldable porous materialconforms to or occupies the inner spatial dimensions of each compartment130. Within each compartment 130, an initial volume 142 of moldableporous ceramic material can exceed or slightly exceed the volumetriccapacity of the compartment 130 by way of the moldable porous ceramicmaterial exhibiting a depth or thickness that exceeds the depth D_(TC)of a base tray compartment 130, for instance, in a manner indicated orgenerally indicated in FIG. 9.

A fourth process portion 178 involves hardening or curing the moldableporous ceramic material and bonding the porous material to the innersurfaces (i.e., inner bottom surfaces 110 within the base tray 100 andcompartment sidewalls corresponding to ridges 120) defining eachcompartment 130. Once the porous material is securely retained within orbonded to compartment inner surfaces, a fifth process portion 180involves machining or polishing the porous material (i.e., each porousmaterial volume 140) as well as portions of the base tray 110 such asexposed upper surfaces 122 of base tray ridges 120 and an exposed uppersurface 108 of the base tray outer border 106 in order to simultaneouslyprovide exposed, upper, or outer surfaces of porous material volumes140, exposed upper surfaces 122 of base tray ridges 120, and the exposedupper surface 108 of the base tray outer border 106 with a very highdegree of planarity, thereby defining a highly uniform wafer tableplanar surface 190 upon which wafers and film frames can be securelyretained. Once planarized, each porous material volume 140 correspondingto any given compartment 130 is identical or essentially identical tothe volume of the compartment 130.

A sixth process portion 182 involves coupling or mounting the planarizedwafer table structure 5 to a displaceable wafer table or stage assembly(e.g., an x-y wafer stage), and coupling vacuum openings 20 within theplanarized wafer table structure 5 to a set of stage assembly vacuumlines, links, and/or valves, such that vacuum force can be selectivelyactuated and applied to wafers 10 or film frames 30 disposed upon thewafer table planar surface 190.

In contrast to certain prior wafer table designs in which regions ofporous material are separated by partitions made or substantially madeof one or more metals, and/or which utilize an outer receptaclestructure made or substantially made of one or more metals, variousembodiments of wafer table structures in accordance with the presentdisclosure avoid or exclude ridges 120 made or substantially made of oneor more metals, and typically further avoid or exclude a base tray 100that is made or substantially made of one or more metals. Moreparticularly, in prior wafer table designs that include upper or exposednon-porous wafer table surfaces that are at least partially orsubstantially made of metal, as well as upper or exposed porous wafertable surfaces that are at least substantially made of a ceramicmaterial, such metal surfaces have quite different machining, grinding,or polishing characteristics, properties, or behavior than the porousceramic material surfaces. During a machining, grinding, or polishingprocess, the metal surfaces will not planarize at the same rate or asreadily as the porous ceramic material surfaces. Moreover, the metalsurfaces can readily damage standard machining, grinding, or polishingelements, devices, or tools (e.g., polishing heads). The inclusion ofmetal surfaces makes the machining, grinding, or polishing processsignificantly more difficult, expensive, and time consuming compared towafer table structures manufactured in accordance with embodiments ofthe present disclosure.

Furthermore, the difference between the machining, grinding, orpolishing characteristics of the exposed metal surfaces and the exposedporous ceramic surfaces significantly increases the likelihood that thefinal as-manufactured wafer table surface will exhibit undesirable orunacceptable non-planarity, or insufficient planarity, across one ormore sections or regions of the wafer table surface. Such prior wafertable designs are therefore not well suited for the inspection of largediameter, thin wafers 10 having fragile die 12 thereon, such as 12-inchor larger sawn wafers 10 carried by film frames 30 which carry small orultra-small die 12. In contrast, wafer table structure embodiments inaccordance with the present disclosure do not suffer from this drawback,and provide a highly uniform or ultra-uniform planar wafer table surface622 that is very well suited to the inspection of such types of wafers10 or film frames 30.

The end result of a wafer table structure manufactured in accordancewith embodiments of the present disclosure is a wafer table 620 that (a)excludes or omits grooves or vacuum holes (e.g., drilled vacuum holes)on the wafer table surface 622 that can adversely affect the planarityof the wafer table surface 622 and result in one or more of theassociated problems previously described; (b) has a very high orultra-high planarity wafer table surface 622 suitable for handling (i)both wafers 10 and film frames 30, thereby eliminating the need forwafer table conversion kits, and (ii) very small or ultra-small die 12(e.g., 0.5 mm×0.5 mm square, or smaller) residing on very thin orflexible wafers (e.g., 75 μm, 50 μm, or thinner), as the planar wafertable surface 622 facilitates the positioning and maintenance of suchdie 12 in/on a single plane, which may be difficult to achieve usingconventional wafer table designs; and (c) structurally straightforward,low cost, and easy to manufacture, particularly compared to conventionalwafer table designs which include grooves or machined/drilled vacuumholes on their wafer table surface, and/or exposed metal materials ontheir wafer table surface (e.g., metal plates, or a number of metalpartitions across the wafer table surface).

Aspects of a Representative Wafer Alignment Station

Returning again to the description of other portions of the system 200shown in FIG. 3A, the wafer (pre)alignment station 400 can includeessentially any type of alignment apparatus or device configured toestablish an initial wafer orientation or alignment relative to portionsor elements of the wafer alignment station 400 and/or the inspectionsystem 600 based upon the position(s) or orientation(s) of one or morewafer alignment features or structures in relation to the waferalignment station 400 or the inspection system 600. Such wafer alignmentfeatures can include a major flat and possibly a minor flat, in a mannerunderstood by one of ordinary skill in the relevant art. In a number ofembodiments, the wafer alignment station 400 is conventional.

Aspects of a Representative Misalignment Inspection System

As previously described, the rotational misalignment of a wafer 10 withrespect to a film frame 30 can result in decreased inspection throughputas more image capture events or frames would be required before anentire-die image of a rotationally misaligned die 12 can be captured andprocessed. In the description hereafter, particular embodiments of anapparatus and process for detecting wafer-to-film frame rotationalmisalignment are described with reference to FIGS. 3A and FIGS. 10A-10C.

The misalignment inspection system 500 includes an apparatus or a set ofdevices configured for determining, detecting, or estimating a waferrotational misorientation/misalignment direction and a correspondingwafer rotational misorientation/misalignment angle, magnitude, or valuefor a wafer 10 mounted on a film frame 30. Depending upon embodimentdetails, the misalignment inspection system 500 can include a film framesupport or positioning apparatus or device; one or more illumination oroptical signal sources (e.g., a set of broadband and/or narrowband lightsources, such as LEDs); and/or one or more illumination or opticalsignal detectors or image capture devices. The misalignment inspectionsystem 500 can also include a processing unit (e.g., within portions ofan embedded system that includes a microcontroller configured forexecuting program instructions, plus a memory in which such programinstructions can be stored; and signal communication or input/outputresources).

Various misalignment inspection system embodiments are provided in thedescription hereafter, in which the misalignment inspection system 500in some embodiments is configured for determining misalignmentangles/misalignment directions and angular magnitudes by way ofoptically detecting the orientation of one or more wafer structuraland/or visual features such as wafer gridlines or a set of flatsrelative to one or more film frame structural and/or visual features,for instance, film frame registration features 34 a-b, or spatialdirections associated with such film frame features. In otherembodiments, the misalignment inspection system 500 is additionally oralternatively configured for determining misalignment directions andmisalignment angular magnitudes by way of capturing at least one imageof a wafer 10 disposed upon a film frame 30, and performing imageprocessing operations involving a comparison between the capturedimage(s) of the wafer 10 and a set of reference axes that correspond tothe FOV 50 of an image capture device, such as an image capture devicewithin the misalignment inspection system 500 and/or within theinspection system 600.

Furthermore, as described below, the determination of and compensationfor a wafer-to-film frame misalignment angle in accordance with anembodiment of the present disclosure can avoid, omit, or exclude, oreliminate the mechanical registration of the film frame 30 relative tothe image capture device. Alternatively, in certain embodiments, thedetermination of a wafer-to-film frame misalignment angle can involvethe mechanical registration of a film frame 30 relative to an imagecapture device (e.g., as a prior operation, or as an initial operation)by way of mating engagement of film frame registration features 34 a-bwith one or more registration elements, in a manner understood by one ofordinary skill in the relevant art.

In various embodiments, the determination of a misalignment angulardirection and a corresponding misalignment angular magnitude occurs byway of image processing operations; and compensation or correction for arotational misalignment of a wafer relative to a film frame on which thewafer is mounted and/or an image capture device FOV occurs by way ofrotating the film frame across the rotational misalignment angularmagnitude, in a direction opposite to the misalignment angulardirection. Embodiments in accordance with the present disclosure canthus omit or avoid mechanical registration of the film frame 30 relativeto an image capture device (e.g., a first image capture device and/or asecond image capture device) by way of mating engagement of film frameregistration features 34 a-b with a set of film frame registrationelements or structures.

FIG. 10A is a schematic illustration of a misalignment inspection system500 configured for determining an extent of rotational or angular wafermisorientation/misalignment relative to a film frame 30 in accordancewith an embodiment of the present disclosure. In an embodiment, themisalignment inspection system 500 includes an image capture device 540coupled to a misalignment processing unit 510. The misalignmentprocessing unit 510 is configured for executing program instructions(e.g., software) for determining or estimating the direction andmagnitude of angular misalignment of a wafer 10 relative to a film frame30. The misalignment processing unit is further communication with thesystem controller 1000, which is configured for communication with thesecond handling subsystem 300 and the inspection system 600.

The misalignment inspection system embodiment shown in FIG. 10A isconfigured for determining wafer-to-film frame misalignment by way ofcomparing or referencing wafer structural features to film framestructural features. More particularly, individual die 12 on a wafer 10are typically visually identifiable or separated by grid lines, such ashorizontal grid lines 6 and vertical grid lines 8, as understood by oneof ordinary skill in the relevant art. If the wafer's horizontal orvertical gridlines 6, 8 exhibit a predetermined or standard referenceorientation with respect to a set of film frame reference feature(s)(e.g., the wafer's horizontal or vertical gridlines 6, 8 aresubstantially parallel or perpendicular to particular predetermined filmframe reference feature(s)), then the wafer 10 is properly alignedrelative to the film frame 30, and correspondingly the wafer's die 12will be properly aligned relative to the inspection system's imagecapture device FOV (thereby maximizing inspection throughput). On theother hand, if the wafer's horizontal or vertical gridlines 6, 8 do notexhibit the predetermined or standard reference orientation with respectto the set of film frame reference feature(s) (e.g., the wafer'shorizontal or vertical gridlines 6, 8 are not substantially parallel orperpendicular to the particular predetermined film frame referencefeature(s)), the wafer 10 is rotationally misaligned relative to thefilm frame 30, and the wafer's die will be misaligned with respect tothe inspection system image capture device FOV in the absence ofcorrection or compensation for such rotational wafer-to-film framemisalignment, thereby reducing inspection throughput. In multipleembodiments, the angular direction and angular magnitude of the wafer'smisorientation/misalignment relative to the film frame 30 can beascertained by determining a wafer misalignment angle. θ_(W) which iscorrelated with or which indicates or defines an angular disposition,offset, or displacement (e.g., as a number of degrees or radians) of oneor more wafer gridlines 6, 8 relative to at least one film frame flat 35a-d. The wafer misalignment angle θ_(W) can indicate or include anangular misalignment direction (e.g., +/−direction) and an angularmisalignment magnitude (e.g., e.g., a number of degrees or radians).

When a film frame 30 is under consideration by the misalignmentinspection system of FIG. 10A, the misalignment inspection system imagecapture device 540 captures one or more images of the wafer 10 disposedupon the film frame 30 and generates corresponding image data. Theimage(s) captured by the misalignment inspection system image capturedevice 540 include (a) one or more wafer regions along which wafer gridlines 6, 8 at least partially extend (e.g., which extend along or acrossa significant or substantial portion of the wafer's surface area); and(b) portions (e.g., significant or substantial portions) of one or morefilm frame flats 35 a-d relative to which the angular orientations ofthe grid line(s) 6, 8 within the captured image(s) can be determined orestimated. Thus, the misalignment inspection system image capture device540 is disposed relative to the film frame 30 such that portions of atleast one wafer gridline 6, 8 (e.g., a significant portion of the lengthof one or more gridlines 6, 8) and at portions of least one referencefilm frame flat 35 a-d (e.g., a significant portion of the length of oneor more film frame flats 35 a-b) lie within a misalignment field of viewFOV_(M) 550 of said image capture device 540.

The aforementioned image data is communicated to the misalignmentprocessing unit 510, which can perform image processing operations(e.g., conventional image processing operations performed by way ofprogram instruction execution, in a manner understood by one of ordinaryskill in the relevant art) to analyze the image data and determine orestimate the wafer misalignment angle θ_(W), which indicates thedirection and magnitude of the angular misalignment of the wafer 10relative to its film frame 30 (in a manner correlated with the angularorientation of the captured wafer gridline(s) 6, 8 relative to thecaptured film frame flat(s) 35 a-d). One of ordinary skill in the artwill understand that the capture of at least a significant length orspatial extent of one or more wafer gridlines 6, 8 (e.g., at least 3-5cm) and at least a significant length or spatial extent of a one or moreframe flats 35 a-b (e.g., at least 2-4 cm), rather than a small segmentor section of such wafer gridlines 6, 8 and film frame flats 35 a-b,respectively, facilitates enhanced accuracy determination of the wafermisalignment angle θ_(W).

FIG. 10B is a schematic illustration showing representative aspects ofdetermining a wafer misalignment angle θ_(W) by a misalignmentinspection system 500 such as that shown in FIG. 10A. In therepresentative embodiment shown in FIGS. 10A and 10B, the misalignmentsystem image capture device 540 is configured such that it can capturewithin its misalignment field of view FOV_(M) 550 at least approximately20%-50% (e.g., at, least approximately 25%-33%), of the surface regionof the wafer 10 that is closest to the first film frame flat 35 a (e.g.,corresponding to a wafer region in which a wafer flat or notch 11 isexpected to be disposed), and the majority of the length of the firstfilm frame flat 35 a proximate to this region of the wafer 10, for thelargest film frame 30 that the system 200 is configured to handle (e.g.,film frames 30 carrying 16-inch wafers 10). For smaller film frames 30(e.g., film frames 30 carrying 12-inch or 8-inch wafers), such amisalignment system image capture device 540 can capture larger portionsof such Smaller film frame's exposed surface areas.

In various embodiments, a single misalignment system image capturedevice 540 can be configured to capture images of each size of filmframe 30 that the system 200 is configured to handle. Other embodimentscan include multiple misalignment system image capture devices 540, forinstance, a first image capture device 540 configured for capturing afirst image corresponding to a first surface region (e.g., a lowersurface region) of a wafer 10 and a corresponding first film frame flat35 a, and a second image capture device 540 configured for capturing asecond image corresponding to another surface region of the wafer 10(e.g., an upper surface region) and a corresponding other film frameflat 35 c. The capture of the first and second images can occursimultaneously, substantially simultaneously, or sequentially. The firstand second image capture devices can have identical or differentmisalignment fields of view FOV_(M) 550, depending upon embodimentdetails.

In an embodiment, the misalignment processing unit 510 can determine oridentify a reference wafer gridline, such as a vertical wafer gridline 6that terminates closest to or at the wafer notch 11 or a midpoint of awafer flat, and can generate a corresponding reference extended virtualor mathematical gridline 568 along which the vertical wafer gridline 6is a line segment, and which extends to or past the film frame's firstflat 35 a. The misalignment processing unit 510 can additionallydetermine or estimate an angle between the first film frame flat 35 aand the reference extended gridline 568, which is correlated with thewafer misalignment angle θ_(W). For instance, as indicated in FIG. 10B,based upon or at an intersection point between the reference extendedgridline 568 and a determined or calculated line or line segment alongwhich the first film frame flat 35 a is a line segment, the misalignmentprocessing unit 510 can determine an acute angle θ_(W). One of ordinaryskill in the relevant art will recognize that the wafer misalignmentangle θ_(W) is given by 90°−α_(W). Other embodiments can additionally oralternatively perform similar, analogous, or other types of calculationsbased upon standard geometrical and/or trigonometric relationships, in amanner understood by one of ordinary skill in the relevant art.

The misalignment processing unit 510 can communicate the wafermisalignment angle θ_(W) to the system control unit 1000 and/or thesecond handling subsystem 300 such that the wafer misalignment angleθ_(W) can be stored in a memory (e.g., buffered). The second handlingsubsystem 300 can receive, retrieve, or access the wafer misalignmentangle θ_(W) corresponding to a film frame 300 being handled, and canrotate the entire film frame 300 opposite to the wafer misalignmentangle θ_(W) to correct the wafer-to-film frame misalignment (e.g., underthe control of program instruction execution).

FIG. 10C is a schematic illustration showing a misalignment inspectionsystem 500 configured for determining an extent of rotational or angularwafer misorientation/misalignment relative to a film frame 30 inaccordance with another embodiment of the present disclosure. In anembodiment, the misalignment inspection system 500 of FIG. 10C includesan image capture device 540 coupled to a misalignment processing unit510, in a manner similar or analogous to that described above inrelation to FIGS. 10A and 10B.

As understood by one of ordinary skill in the relevant art, within aninspection system 600, an image capture device (e.g., a camera) 640provides a field of view FOV₁ 650 which corresponds to inspection systemFOV axes X₁ and Y₁. Correspondingly, within the misalignment inspectionsystem 500, an image capture device 540 provides a field of view FOV_(M)550 which corresponds to misalignment inspection system FOV axes X_(M)and Y_(M).

When a film frame 30 carrying a wafer 10 having zero misalignment (i.e.,having a misalignment angle θ_(W) of zero degrees) with respect to thefilm frame 30 is registered relative to the misalignment inspectionsystem's image capture device 540, the wafer's horizontal and verticalgrid lines 6, 8 will have a predetermined orientation relative to themisalignment inspection system FOV axes X_(M) and Y_(M). For instance,under such conditions, the wafer's horizontal and vertical grid lines 6,8 are aligned parallel to or geometrically coincident with, themisalignment inspection system FOV axes X_(M) and Y_(M). Similarly, whena film frame 30 carrying a wafer 10 having zero misalignment relative tothe film frame 30 is registered with respect to the inspection system'simage capture device 640, the wafer's horizontal and vertical grid lines6, 8 will have a predetermined orientation relative to the inspectionsystem FOV axes X₁ and Y₁ (e.g., the wafer's grid lines 6, 8 will beparallel to or geometrically coincident with the inspection system FOVaxes X₁ and Y₁.

When a film frame 30 is under consideration for the determination ofwafer misalignment relative to the film frame 30, the misalignmentinspection system's image capture device 540 captures one or more imagesof the wafer 10 disposed upon the film frame 30 and generates image datacorresponding thereto. Such image data is communicated to themisalignment processing unit 510, which can perform image processingoperations (e.g., conventional image processing operations, in a mannerunderstood by one of ordinary skill in the relevant art) to analyze theimage data and determine the wafer misalignment angle θ_(W) based upon amisorientation or misalignment of one or more horizontal wafer gridlines 6 and/or one or more vertical wafer grid lines 8 with respect tothe misalignment inspection system FOV axes X_(M) and Y_(M).

FIG. 10D is a schematic illustration showing aspects of determining anextent of rotational or angular wafer misalignment relative to a filmframe 30 by a misalignment inspection system 500 such as that shown inFIG. 10C. As indicted in FIG. 10D, the extent to which a wafer'shorizontal and vertical grid lines 6, 8 are rotationally or angularlyoffset from the misalignment inspection system FOV axes X_(M) and Y_(M)defines the wafer misalignment angle θ_(W), The misalignment processingunit 510 can communicate the wafer misalignment angle θ_(W) to thesystem control unit 1000 and/or the second handling subsystem 300, suchthat the wafer misalignment angle θ_(W) can be stored in a memory, andaccessed by the second handling subsystem 300 to correct the rotationalmisalignment of the wafer 10 relative to its film frame 30.

As described in detail below, when the second handling subsystem 300 ishandling a given film frame 30, the second handling subsystem 300 canaccess or retrieve (e.g., from a memory) a wafer misalignment angleθ_(W) corresponding to the film frame 30, and rotate the film frame 30to correct for misalignment of the wafer 10 carried by the film frame30, for instance, when the wafer misalignment magnitude exceeds amaximum misalignment angle threshold θ_(W-Max) (i.e., whenθ_(W)>θ_(W-Max)), which can be predetermined, programmable, orselectable. The industry standard threshold is 15 degrees forwafer-to-film frame rotational misalignment. However, the experience ofthis patent applicant indicates that wafer-to-film frame rotationalmisalignment of more than 5 degrees should require adjustment becauseincreasingly, die 12 are being manufactured smaller and wafer sizes aregetting larger. Any delay in image capture of an entire-die or whole-dieimage for image processing as a result of wafer-to-film frame rotationalmisalignment, and hence inspection process throughput reduction, wouldbe magnified or exacerbated given the large number of die carried bylarger wafers (for instance, 10,000 or more die, such as 20,000-30,000,die), depending on die size and wafer size. For instance, θ_(W-Max) canbe defined to have an angular magnitude of approximately 10 degrees, 7.5degrees, 5 degrees, or 3 degrees. In general, the maximum misalignmentangle threshold can depend upon die size and inspection system imagecapture device FOV 650 in relation in relation thereto.

As further described below, the second handling subsystem 300 cancorrect for wafer-to-film frame rotational misalignment withoutintroducing any delay in film frame handling operations, that is,without causing a decrease in film frame handling or inspection processthroughput. For instance, the second handling subsystem 300 can rotate afilm frame 30 to correct for wafer-to-film frame rotational misalignmentwhile transferring the film frame to the wafer table surface 622, in thesame amount of time required to transfer a film frame 30 for which thewafer misalignment angle θ_(W) is zero or essentially zero.Consequently, in certain embodiments, essentially any wafer-to-filmframe rotational misalignment that is detectable (e.g., reliably orrepeatably detectable) by the misalignment inspection system 500 can becommunicated to and/or acted upon the second handling subsystem 300,irrespective of a maximum misalignment angle threshold θ_(W-Max), suchthat the second handling subsystem 300 can automatically correct forwafer-to-film frame rotational misalignment on every or essentiallyevery film frame 30 to be inspected, without affecting film framehandling throughput and inspection throughput.

In a number of embodiments, the misalignment inspection system 500 canbe independent, separate, or distinct from one or both of the first andsecond handling subsystems 250, 300. For instance, the misalignmentinspection system 500 can include or be an apparatus that is distinctfrom each of the first and second handling subsystems 250, 300, yetwhich is internal to the system 200, for instance, carried by thesystem's support structure 202. Alternatively, the misalignmentinspection system 500 can be external to or remote from the system 200(e.g. in a different room), for instance, disposed away from thesystem's support structure 202 and configured for operating at leastsubstantially independently of the system 200 to determine for a numberof film frames 30 disposed within a film frame carrier correspondingwafer angular misalignment directions and angular misalignmentmagnitudes, which can be stored in a memory and/or communicated toand/or retrieved by the system's control unit 1000 or the secondhandling subsystem 300 to facilitate wafer misalignment correctionoperations. In certain embodiments, the misalignment inspection system500 can also include one or more film frame registration elements (e.g.,mechanical registration elements configured for mating engagement withfilm frame registration features 34 a-b), such that the misalignmentinspection system 500 performs mechanical film frame registration priorto determining an extent of wafer-to-film frame misalignment.

In particular embodiments, portions of the misalignment inspectionsystem 500 can include one or more portions of the second handlingsubsystem 300, the wafer table 620, and/or possibly portions of theinspection system 600 (e.g., a wafer table assembly 610 and one or moreimage capture devices). For instance, after a film frame 30 has beentransferred to and placed upon the wafer table 620, an inspection systemimage capture device 640 can a set of capture images of the wafer 10carried by the film frame 30 and generate one or more correspondingimage data sets. A processing unit coupled to the inspection system 600can analyze such image data sets to determine a wafer misalignment angleθ_(W), for the wafer 10 carried by the film frame 30 disposed on thewafer table 620. The processing unit can further compare the wafermisalignment angle θ_(W) to the maximum misalignment angle thresholdθ_(W-Max) to determine if the magnitude of angular wafer misalignmentexceeds the maximum misalignment angle threshold θ_(W-Max). If so, theprocessing unit can issue a misalignment correction request to thesecond handling subsystem 300, which can pick up the film frame 30 fromthe wafer table surface 622, and rotate the film frame 30 in a directionand by an angular amount that corrects or adjusts for the misalignmentof the wafer 10 relative to its film frame 30. The second handlingsubsystem 300 can then place the film frame 30 back upon the wafer tablesurface 622, after which film frame inspection can begin under properwafer to inspection system image capture device FOV 650 alignmentconditions.

In other embodiments, portions of the misalignment inspection system 500can include the first handling subsystem 200; plus an image capturedevice 540 that is disposed external to a film frame cassette, where theimage capture device 540 is configured for capturing a set of images ofa wafer 10 on a film frame 30 after the first handling subsystem 200 haswithdrawn the film frame 30 from the film frame cassette. The firsthandling subsystem 200 can position the film frame 30 beneath themisalignment inspection system's image capture device 540, which cancapture a set of images of the wafer 10 carried by the film frame 30 andcommunicate corresponding image data to the misalignment processing unit510 for analysis/processing and the determination of a correspondingwafer misalignment angle θ_(W). In embodiments in which a portion of thefirst handling subsystem 200 such as an end effector 270 includes amechanical film frame registration element 282, the film frame 30 can bemechanically registered with respect to the first handling subsystem 200in association with withdrawal of the film frame 30 from the film framecassette. The first handling subsystem 200 can position the film frame30 relative to the misalignment inspection system's image capture device540 in accordance with a known or predetermined positioning, such thatthe film frame 30 is mechanically registered with respect to themisalignment inspection system FOV axes X_(M) and Y_(M).

In still further embodiments, the second handling subsystem 300 caninclude, implement, or be combined or effectively combined with one ormore portions of the misalignment inspection system 500. For instance,one or more portions of the second handling subsystem 300 can include orbe positionable relative to a number of optical and/or image captureelements. In certain embodiments, after a film frame 30 has beentransferred to the second handling subsystem 300, the second handlingsubsystem 300 can determine a wafer misalignment angle θ_(W)corresponding to a film frame 30. The second handling subsystem 300 canthen rotate the film frame 30 to correct for the wafer-to-film framerotational misalignment indicated by the wafer misalignment angle θ_(W),thereby establishing a proper orientation of the die 12 carried by thefilm frame 30 relative to the inspection system image capture device FOV650. The second handling subsystem 300 can also transfer the film frame30 to the wafer table 622 (e.g., simultaneous with film frame rotation,or subsequent to film frame rotation).

Aspects of Purely Mechanical Versus Image Processing Assisted Film FrameRegistration

One having ordinary skill in the relevant art will further recognizethat if a wafer carried by a film frame is correctly mounted on the filmframe with no or minimal rotational misalignment relative to the filmframe, mechanical registration of the film frame by way of engaging filmframe registration features 34 a-b with film frame registration elementsor structures results in the film frame being properly aligned relativeto the FOV of an inspection system image capture device, whichcorrespondingly results in the wafer being properly or acceptablyaligned relative to the inspection system image capture device FOV.

However, when a wafer is originally mounted to a film frame, the wafermay be rotationally misaligned relative to the film frame. Consequently,when rotational misalignment of the wafer relative to the film frameexists, mechanical registration of a film frame fails to resolve therotational misalignment of the wafer relative to the inspection systemimage capture device FOV. In other words, when such rotationalmisalignment exists, and has a magnitude beyond or outside of anacceptable range, mechanical registration of the film frame relative toan image capture device FOV is of no benefit with respect to ensuringthat the wafer is properly aligned relative to the image capture deviceFOV.

Various embodiments in accordance with the present disclosure areconfigured for performing an optical or image processing assistedregistration of a wafer carried by a film frame relative to an imagecapture device FOV, which involves image processing operations todetermine a wafer rotational misalignment angle and a correspondingwafer rotational misalignment direction. Consequently, a mechanical filmframe registration procedure can be omitted, avoided, or excluded. Anindividual of ordinary skill in the relevant art will recognize that theelimination of a manufacturing procedure, for instance, a film framehandling procedure such as a mechanical film frame registrationprocedure involving the mating engagement of film frame registrationfeatures 34 a-b with one or more registration elements, saves time andtherefore can increase throughput. Several embodiments in accordancewith the present disclosure can render a mechanical film frameregistration procedure unnecessary or redundant, as further describedbelow. While a mechanical film frame registration procedure can still beperformed in some of such embodiments, in multiple embodiments amechanical film frame registration procedure can be avoided oreliminated.

Embodiments of the misalignment inspection system 500 such as that shownin FIGS. 10A-10B are configured for determining (by way of image captureand image processing operations) the wafer misalignment angle θ_(W) byway of determining or analyzing angular relationships between waferstructural or visual features and film frame structural or visualfeatures. Such embodiments can accurately determine the wafermisalignment angle θ_(W), regardless or independent of whether the filmframe 30 has been mechanically registered relative to the inspectionsystem image capture device FOV 650. Provided that the second handlingsubsystem 300 has been registered or aligned relative to the inspectionsystem image capture device 640 (e.g., as part of its installation, oran initial or one-time configuration/setup procedure), once the secondhandling subsystem 300 has rotated a film frame 30 to correct for thepresence of a detected wafer-to-film frame rotational misalignment, thesecond handling subsystem 300 can directly transfer the film frame 30 tothe wafer table surface 622 such that the die 12 carried by the filmframe 30 are properly aligned and exhibit the correct rotationalorientation (e.g., a maximum inspection process throughput orientation)relative to the inspection system image capture device FOV 650. Theinspection system 600 can subsequently directly or immediately initiatefilm frame inspection operations without the need for a separate or anadditional mechanical film frame registration procedure prior toinspection of the film frame 30.

Analogously, embodiments of the misalignment inspection system 500 suchas that shown in FIGS. 10C-10D are configured for determining the wafermisalignment angle θ_(W) by way of determining or analyzing angularrelationships between wafer structural or visual features and one ormore misalignment inspection system FOV axes X_(M) and Y_(M). Suchembodiments can also accurately determine the wafer misalignment angleθ_(W), regardless or independent of whether the film frame 30 has beenmechanically registered relative to the inspection system image capturedevice FOV 650. Provided that the misalignment inspection system imagecapture device 540 has been registered or aligned relative to theinspection system image capture device 640 (e.g., as part of itsinstallation or an initial or one-time configuration/setup procedure),after the second handling subsystem 300 has rotated a film frame 30 tocorrect for wafer-to-film frame rotational misalignment, die 12 on thefilm frame 30 are properly aligned relative to the inspection systemimage capture device FOV 650. The second handling subsystem 300 candirectly transfer the film frame 30 to the wafer table surface 622, andthe inspection system 600 can directly or immediately initiate filmframe inspection operations without the need for a separate oradditional mechanical film frame registration procedure prior toinitiating its inspection of the film frame 30.

By way of (a) the misalignment inspection system's accuratedetermination of a wafer misalignment angle θ_(W) regardless orindependent of whether a film frame 30 has been mechanically registeredrelative to the inspection system image capture device FOV 650 and/oranother portion of the system 200; (b) the second handling subsystem'srotation of the film frame 30 in accordance with θ_(W) (e.g., in adirection opposite to the direction indicated by θ_(W), and through anangular span equal or essentially equal to that indicated by θ_(W)) tocorrect for wafer-to-film frame rotational misalignment, therebyproviding a rotationally corrected film frame 30; and (c) the secondhandling subsystem's transfer of the rotationally corrected film frame30 directly to the wafer table surface 622, embodiments in accordancewith the present disclosure can effectively optically register filmframes 30 relative to the inspection system image capture device FOV650.

As long as the transfer of film frames 30 from the misalignmentinspection system 500 to the second handling subsystem 300 accuratelyand reliably maintains or preserves each film frame's rotationalorientation or disposition prior to the second handling subsystem'sinitiation of film frame rotation operations, such optical/imageprocessing assisted registration of film frames 30 relative to theinspection system image capture device FOV 650 can eliminate the needfor a mechanical film frame registration procedure. As further detailedbelow, the manner in which embodiments in accordance with the presentdisclosure transfer film frames 30 from the first handling subsystem 250to the second handling subsystem 300 ensures or is intended to ensurethat the rotational orientation of any given film frame 30 is accuratelyand reliably preserved between the time at which the misalignmentinspection system 500 captures a set of images of a wafer 10 mounted ona film frame 30 and the time at which the second handling subsystem 300initiates film frame rotation operations based upon the wafermisalignment angle θ_(W).

Furthermore, in multiple embodiments, a film frame handling and opticalor optically assisted registration sequence involving each of (a) themisalignment inspection system's inspection of wafers 10 mounted on filmframes 30 and determination of corresponding wafer misalignment anglesθ_(W); (b) the transfer of film frames 30 from the misalignmentinspection system 500 to the second handling subsystem 300; (c) thesecond handling subsystem's correction of wafer-to-film frame rotationalmisalignment, thereby effectuating an optically/image processingassisted registration of the film frame 30 relative to the inspectionsystem image capture device FOV 650; and (d) the second handlingsubsystem's transfer of rotationally corrected film frames 30 to thewafer table surface 622 avoids introducing additional film framehandling time between the time at which a film frame 30 is retrievedfrom a film frame cassette to the time at which the film frame 30 isplaced upon the wafer table surface 622. Thus, each of (a), (b), (c),and (d) within the aforementioned film frame handling andoptically/image processing based registration sequence avoids decreasingfilm frame handling throughput and hence avoids decreasing inspectionprocess throughput. Moreover, the omission or elimination of aconventional/purely mechanical film frame registration procedure, whichrequires a given mechanical registration time, results in time savingsand a corresponding increase in throughput. In contrast to embodimentsin accordance with the present disclosure, prior systems and methodshave failed to recognize that the elimination of a mechanical film frameregistration procedure is desirable or possible.

To further elaborate, as indicated above in some embodiments themisalignment inspection system 500 includes an image capture device 540configured for capturing images of wafers 10 mounted on film frames 30in association with the first handling subsystem's transfer of the filmframes 30 from a film frame cassette to the second handling subsystem300. For instance, the misalignment inspection system image capturedevice 540 can be disposed above portions of a film frame travel pathalong which a portion of the first handling subsystem (e.g., a roboticarm 260 coupled to an end effector 270, as described below) transports afilm frame 30 to the second handling subsystem 300, such that themisalignment inspection system image capture device 540 captures imagesof the wafer 10 mounted on the film frame 30 as the film frame 30 movesalong this travel path (e.g., “on-the-fly”). The misalignment inspectionsystem 500 can then determine a wafer misalignment angle θ_(W) in amanner identical, essentially identical, analogous, or generallyanalogous to that described above, and communicate the wafermisalignment angle θ_(W) to the second handling subsystem 300. The firsthandling subsystem 250 can transfer the film frame 30 to the secondhandling subsystem 300 in a manner that accurately and reliablymaintains the film frame's rotational orientation with respect to themisalignment inspection system's determination of the wafer misalignmentangle θ_(W), after which the second handling subsystem can correct forwafer-to-film frame rotational misalignment and transfer the film frame30 to the wafer table 622. In still another alternative embodiment, thefirst handling subsystem 250 can be configured for rotating the filmframe 30 to compensate for a rotational misalignment of a wafer 10mounted on a film frame 30, such as by way of a rotatable robotic armassembly that carries the film frame 30 by way of an end effector.

Similar or analogous considerations to those described above withrespect to the omission, elimination, or effective duplication of amechanical film frame registration procedure apply to embodiments inwhich one or more portions of the misalignment inspection system 500 arecombined with or implemented by the second handling subsystem 300, suchthat the second handling subsystem 300 can determine wafer misalignmentangles θ_(W).

Aspects of a Representative First Handling Subsystem

The first handling subsystem 250 includes at least one end effectorbased handling apparatuses or device, such as one or more robotic arms260 coupled to a set of corresponding end effectors 270. The firsthandling subsystem 250 is configured for performing particular types ofwafer handling operations, and certain types of film frame handlingoperations. With respect to wafer handling operations, in severalembodiments, the first handling subsystem 250 is configured for each ofthe following:

-   -   (a) retrieving wafers 10 from one or more wafer sources 210        prior to wafer processing by the inspection system 600, where a        wafer source 210 can include or be a wafer carrier/cassette, or        another processing system or station;    -   (b) transferring wafers 10 to the wafer alignment station 400;    -   (c) transferring initially aligned wafers 10 from the wafer        alignment station 400 to the wafer table 620 (e.g., by        transferring a wafer 10 to and positioning the wafer 10 upon the        ejector pins 612, and subsequently releasing the wafer 10) to        facilitate wafer processing operations;    -   (d) retrieving wafers 10 from the wafer table 620 (e.g., by        capturing a wafer 10 elevated away from the wafer table 620 by        way of the ejector pins 612, and removing the wafer 10 from the        ejector pins 612); and    -   (e) transferring wafers 10 retrieved from the wafer table 620 to        one or more post-processing wafer destinations 220, such as a        wafer carrier or cassette or another processing system or        station.

With respect to film frame handling operations, in several embodimentsthe first handling subsystem 250 is configured for each of thefollowing:

-   -   (a) retrieving film frames 30 from one or more film frame        sources 230 prior to film frame processing by the inspection        system 600, where a film frame source 230 can include or be a        film frame carrier/cassette, or another processing system or        station;    -   (b) in some embodiments, establishing an initial film frame        registration or alignment (which can be maintained relative to        the wafer table 620 and/or one or more elements of the        inspection system 600) by aligning, matching, engaging, or        mating film frame registration features 34 a-b with respect to        at least one first handling subsystem registration element 282        that includes counterpart or complementary registration features        284 a-b, for instance, with further reference to FIG. 11B, by        way of a set of end effectors 270 a-b that includes at least one        end effector 270 a that carries a first handling subsystem        registration element 282;    -   (b) transferring film frames 30 to the second handling subsystem        300; and    -   (c) receiving film frames 30 from the second handling subsystem        300 and transferring received film frames 30 to one or more        post-processing film frame destinations 240, which can include a        film frame carrier or cassette or a film frame processing        station.

In a number of embodiments, an initial film frame registration oralignment relative to the inspection system 600 is established in aconventional manner by way of registration elements carried by the wafertable assembly 610, and the mating engagement of film frame registrationfeatures 34 a-b to such registration elements, in a manner readilyunderstood by one of ordinary skill in the relevant art.

In an embodiment, the first handling subsystem 250 is also configuredfor (d) positioning film frames 30 with respect to the misalignmentinspection system 500 to facilitate the determination or measurement ofwafer angular misalignment magnitudes and directions relative to filmframes 30 that carry the wafers 10.

Aspects of a Representative Second Handling Subsystem

In multiple embodiments, the second handling subsystem 300 is configuredfor the following wafer or film frame handling operations:

For film frame handling:

-   -   (a) exchanging film frames 30 with (i.e., receiving film frames        30 from, and transferring film frames 30 to) the first handling        subsystem 300; and    -   (b) positioning film frames 30 upon the wafer table 620.

For wafer handling:

-   -   (c) selectively applying a flattening force or pressure to        portions of wafers 10 that cannot be sufficiently, completely,        or securely retained upon the wafer table surface 622 as a        result of non-planarity or warpage, in association with wafer        table application of a vacuum force to such non-planar or warped        wafers 10 (and automatic/sensor-based determination of vacuum        force sufficiency); and    -   (d) spatially confining wafers 10 during wafer release from the        wafer table 620, where such release can occur by way of vacuum        force cessation and possible air purge application, and any        ejector pin extension.

In certain embodiments, the second handling subsystem 300 is configuredfor establishing an initial film frame registration or alignmentrelative to one or more portions or elements of the inspection system600 by aligning, matching, engaging, or mating frame registrationfeatures 34 a-b with respect to at least one second handling subsystemregistration element (not shown) that includes counterpart orcomplementary registration features (not shown), in a manner analogousor generally analogous to that indicated above for the first handlingsubsystem 250.

In an embodiment, the second handling subsystem 300 is additionallyconfigured for rotating film frames 30 with respect to rotationalmisalignment information (e.g., the wafer misalignment angle θ_(W))corresponding to the wafer 10 mounted on the film frame 30 determined bythe misalignment inspection system 500. Alternatively, wafer-to-filmframe rotational misalignment can be inspected/determined by theinspection system 600 (e.g., misalignment inspection system 500 can bepart of or implemented by the inspection 600 if the film frame 30 ispositioned on the wafer table 622). As indicated above, the misalignmentinspection system 500 can include the wafer table 620 and an imagecapture device 640 corresponding to the inspection system 600, and thesecond handling subsystem 300 can be configured for (a) positioning filmframes 30 upon the wafer table 620 such that the misalignment inspectionsystem 500 can determine a wafer-to-film frame angular misalignmentdirection and magnitude, and (b) retrieving film frames 30 from thewafer table 620, correcting wafer-to-film frame misalignment, and (c)subsequently placing such film frames 30 back on the wafer table 620.

In view of the foregoing, the first handling subsystem 250 can provide awafer transport interface for transporting wafers 10 between a wafertable location corresponding to wafer table ejector pin positions andwafer sources/destinations other than or external to the wafer table620. The second handling subsystem 300 can provide a film frametransport interface for transporting film frames 30 between the firstwafer handling subsystem 200 and the wafer table 600; a film framerotation interface; a wafer flattening interface; and a wafer lateralconfinement interface. As indicated above, with respect to a process forcorrecting wafer-to-film frame rotational misalignment, the secondhandling subsystem 300 need not perform the correction of suchrotational misalignment while stationary. It can correct the rotationalmisalignment while transporting the film frame 30 enroute to the wafertable 620. This aspect of the design of second handling subsystem 300ensures that no time is lost while performing wafer-to-film framemisalignment correction. Additionally, since it involves rotating thefilm frame 30 by a certain magnitude and direction to correct forwafer-to-film frame rotational misalignment without loss of time, it canbe implemented for every inspection of a wafer 10 mounted on film frame30.

Thus, the second handling subsystem 300 can (a) position film frames 30upon the wafer table 620 in a manner that avoids or overcomes problemsassociated with rotational misalignment of wafers 10 relative to filmframes 30, for instance, without loss of process time to correctrotational misalignment; (b) remove film frames 30 from the wafer table620; (c) overcome insufficient or incomplete wafer surface arearetention by the wafer table 620 due to loss of vacuum force caused bywafer non-planarity or warpage; and (d) prevent unwanted lateraldisplacement of wafers 10 along the wafer table surface 622 followingvacuum force release or interruption, and the application of anyassociated air purge.

In a number of embodiments, the second handling subsystem 300 includeseach of the following:

For film frame handling:

-   -   (a) a rotation compensation apparatus configured for        automatically rotating a film frame 30 to correct for rotational        misalignment of a wafer 10 relative to the film frame 30 (e.g.,        in accordance with an angular misalignment direction and        magnitude, possibly in view of a maximum misalignment angle        threshold or tolerance, which can be correlated with or        correspond to a maximum allowable wafer-to-film frame        misalignment tolerance); and    -   (b) a film frame placement and retrieval apparatus with respect        to the wafer table (“film frame—wafer table placement/retrieval        apparatus) configured for placing film frames 30 upon the wafer        table surface 622 and removing film frames from the wafer table        surface 622.

For wafer handling:

-   -   (a) a flattening apparatus configured for applying a force or        pressure upon portions of a wafer 10 in a direction normal or        substantially normal to the wafer table surface 622 (e.g.,        parallel to the wafer table z axis Z_(wt)) in association with        the application of vacuum force by the wafer table 620; and    -   (b) a confinement or containment apparatus configured for at        least substantially preventing lateral displacement of a wafer        10 along the wafer table surface 622 following cessation of a        vacuum force applied to the wafer 10, and the application of any        associated air burst or purge, to the underside of the wafer 10        by/through the wafer table 620.

In several embodiments, the second handling subsystem 300 includes amultifunction handling, transport, and/or pick and place apparatus thatcombines, integrates, or unifies portions of the rotation compensationapparatus, the flattening apparatus, and the confinement apparatus, asdescribed in detail hereafter.

Aspects of a Representative Multifunction Pick and Place Apparatus

FIGS. 12A-12D are schematic illustrations showing aspects of arepresentative multifunction handling (MFH) apparatus, assembly, unit,or station 300 configured as each of a rotation compensation apparatus,a flattening apparatus, a confinement apparatus, and a film frame—wafertable placement/retrieval apparatus in a combined, integrated, orunified manner for performing wafer and film frame handling operationsin accordance with an embodiment of the present disclosure. In anembodiment, the MFH apparatus 300 includes each of the following:

-   -   (a) a main body, frame element, or housing 302;    -   (b) a plurality of displaceable capture arms 310 coupled to the        housing 302, configured for (i) selectively capturing, securely        holding, and selectively releasing film frames 30 of different        dimensions, sizes, or diameters by way of the application or        cessation of vacuum forces provided to portions of a film        frame's periphery or border, and (ii) selectively constraining        or preventing lateral displacement of wafers 10 along the wafer        table surface 622;    -   (c) a set of vacuum elements (e.g., vacuum linkages, lines,        and/or valves) 318 coupled to the plurality of capture arms 310,        which facilitate the control of vacuum forces or negative        pressures applied by the plurality of capture arms 310 to film        frames 30;    -   (d) a capture positioning assembly 320 that includes a capture        arm displacement motor or driver 330 and a displacement linkage        334 coupled to the plurality of capture arms 310, for        controllably displacing the plurality of capture arms 310 to        multiple (e.g., selectable or predetermined) distinct positions        or distances transverse to and away from or towards a common        axis, such as a pick and place z axis Z_(pp) corresponding or        approximately corresponding to a midpoint, center, or centroid        of a film frame 30 or a wafer 10 carried thereby, where each        such distinct position or distance away from or toward Z_(pp)        can correspond to a different film frame dimension, size, or        diameter;    -   (e) a rotational misalignment compensation motor or driver 340        configured for selectively and concurrently rotating each of the        plurality of capture arms 310 (i.e., collectively rotating the        plurality of capture arms 310) in a common direction about a        common axis of rotation, such as the pick and place z axis        Z_(pp), to facilitate wafer angular misalignment correction        operations;    -   (f) a support member or arm 352 configured for carrying the        housing 302; and    -   (g) a vertical displacement motor or driver 350 configured for        selectively or controllably displacing the plurality of capture        arms 310 along a vertical direction parallel to each of the        wafer table z axis Z_(wt) and the pick and place z axis Z_(pp)        (i.e., perpendicular or substantially perpendicular to the wafer        table surface 622), for instance, by way of vertical        displacement of the housing 302, to facilitate film frame—wafer        table placement/retrieval.

In some embodiments, the MFH apparatus 300 can be disposed relative to,or configured for carrying, implementing, or optically communicatingwith a misalignment inspection system image capture device 540 which isconfigured for capturing images of a film frame 30 in a manner describedor indicated above with reference to FIGS. 10A-10D. For instance, theMFH apparatus housing 302 can carry a set of optical and/or imagecapture elements, such an image capture device 540 that includes a setof image sensors, within or upon its housing 302. Alternatively, thehousing 302 can be disposed below such an image capture device 540 (inwhich case one or more portions of the housing can include one or moreopenings to facilitate image capture therethrough). As a furtheralternative, the housing 302 can carry a set of optical elements such asa microlens array which is couplable to an optical fiber bundle, andwhich is configured for communicating optical or imaging signalscorresponding to film frame images to an image capture device (e.g., acamera) that can be disposed external to or away from the housing 302.In such an embodiment, the set of optical elements can include a numberof illumination sources (e.g., LEDs).

FIG. 12B is a schematic illustration showing portions of a capture arm310 in accordance with an embodiment of the present disclosure. In anembodiment, each capture arm 310 includes an arm member 312 that extendsin a direction or within a plane substantially transverse to the pickand place z axis Z_(pp), and a corresponding terminal portion or endsegment 314 that projects or extends away from the arm member 312 in adirection substantially parallel to Z_(pp). Each arm member 312 and itscorresponding end segment 314 includes a channel or passage therethroughconfigured for communicating, providing, or supplying a vacuum force.Furthermore, each end segment 314 carries, includes, or is coupled to asoft and resiliently deformable or pliable tip element 316 thatfacilitates secure vacuum retention of film frames (e.g., by way of endsegment positioning at a peripheral portion or outer border of a filmframe 30), minimal or negligible unwanted air intrusion or vacuumleakage, and reduced, minimal, or negligible likelihood of inducingdamage or defects if positioned adjacent to or upon the surface of awafer 10.

Aspects of Representative Film Frame Capture and Release

FIG. 12C is a schematic illustration showing portions of a capturepositioning assembly 320 in accordance with an embodiment of the presentdisclosure, and a representative first positioning of the plurality ofcapture arms 310 at a first position or radial distance away from thepick and place z axis Z_(pp), corresponding to a first film framediameter or cross sectional area. FIG. 12C is a schematic illustrationshowing portions of the capture positioning assembly 320, and arepresentative second positioning of the plurality of capture arms 310at a second position or radial distance away from Z_(pp), correspondingto a second film frame diameter or cross sectional area, which issmaller than the first film frame diameter or cross sectional area.

The capture arm positioning motor 330 is configured for selectivelyorienting the plurality of capture arms 320 relative to each other andthe pick and place z axis Z_(pp), such that the plurality of capturearms 320 can be selectively disposed relative to or at multiple capturepositions, where each capture position corresponds to a distinct filmframe dimension, size, area, or diameter. In the embodiment shown inFIGS. 12B-12C, the selective positioning of the plurality of capturearms 310 occurs by way of pulleys 332 a-e. More particularly, any givencapture arm 310 a-d is coupled to a corresponding pulley 332 a-d in amanner that facilitates rotational of its arm member 312 a-d about acentral axis of the capture arm's corresponding pulley 332 a-d; and thepulleys 332 a-d corresponding to each capture arm 310 a-d aremechanically coupled or linked to each other by way of the displacementlinkage 334, which can be, for instance, a belt or band. An additionalpulley 332 e can be configured for regulating, providing, controlling,or selecting an amount of tension upon the displacement linkage 334. Thecapture arm positioning motor 330 is coupled to one of the pulleys 332d, which serves as a drive pulley 332 d.

A rotational motion or force applied by the capture arm positioningmotor 330 to the drive pulley 332 d results in the simultaneous oressentially simultaneous and precise and controlled rotation of eachpulley 332 a-e by way of the displacement linkage 334, and hencesimultaneous rotation of each arm member 312 a-d about the central axisof its corresponding pulley 332 a-d. Depending upon the direction inwhich the motor 330 rotates the drive pulley 332 d, the rotation of armmember 312 a-d results in radial displacement or translation of eachcapture arm's tip element 314 a-d in a direction toward or away from thepick and place z axis Z_(pp). Consequently, the tip elements 314 a-dcorresponding to the plurality of capture arms 310 are collectivelydisplaced or translated transverse to, or in a common transverse planerelative to, the pick and place z axis Z_(pp), in a manner thatfacilitates the automatic adjustment of a radial distance at which eachtip element 314 a-d is disposed from Z_(pp). Particular distinct radialdistances (e.g., selectable or predetermined distances) of the tipelements 314 a-d away from Z_(pp) correspond to and facilitate thecapture of film frames 30 of different dimensions, sizes, or diameters(e.g., larger and smaller diameters). The ability of the tip elements316 to move radially in equidistance towards or away from Z_(pp) alsofacilitates the gentle pressing or holding down of a wafer 10 (e.g., awarped wafer 10) in association with a wafer handling process describedin detail below.

Once the plurality of capture arms 310 is disposed at a radial distanceaway from Z_(pp) that corresponds to the size of a film frame 30 underconsideration, the plurality of capture arms 310 can be positioned suchthat the capture arm tip elements 316 are in contact with peripheralportions of the film frame 30. Vacuum can then be activated such that avacuum force or negative pressure is applied to peripheral portions ofthe film frame 30 through the plurality of capture arms 310. Theplurality of capture arms 310 can securely carry, hold, or retain thefilm frame 30 by way of the vacuum force applied therethrough.Analogously, the plurality of capture arms 310 can release the filmframe 30 by way of cessation of the vacuum force applied therethrough.

In various embodiments, the MFH apparatus 300 is configured forpositioning relative to portions of the first handling subsystem 250(e.g., an end effector 270), such that the plurality of capture arms 310can capture a film frame 30 from the first handling subsystem 250. Forinstance, when an end effector 270 has captured a film frame 30, the endeffector delivers a vacuum force or negative pressure upon peripheralportions of the film frame's underside, in a manner understood by one ofordinary skill in the relevant fart. When the first handling subsystem'send effector 270 carries a film frame 30, the plurality of capture arms310 can be positioned above the end effector 270 and over the upper ortop side or surface of the film frame 30. The plurality of capture arms310 can then be vertically displaced relative to the end effector 270(e.g., by the vertical displacement motor 350, and/or verticaldisplacement of a robotic arm 260 coupled to the end effector 270) suchthat the plurality of capture arm tip elements 316 contact peripheralportions of the film frame's top surface. During such verticaldisplacement of the plurality of capture arms 310, vacuum can beactivated, such that a vacuum force or negative pressure flows throughthe plurality of capture arms. A set of vacuum sensors coupled to thesecond handling subsystem 300 can automatically monitor the vacuumpressure within vacuum lines coupled to the plurality of capture arms310. Once the plurality of capture arms 310 comes into contact withperipheral portions of the film frame's upper side, the plurality ofcapture arms 310 can securely attach to or capture the film frame 30 bayway of the vacuum force delivered therethrough. After the vacuumsensor(s) detect that this vacuum force has exceeded a suitable capturethreshold, the end effector 270 which has been holding portions of thefilm frame's underside can release the vacuum force it has been applyingto the film frame's underside, thereby releasing the film frame form theend effector 270 and completing the transfer of the film frame 30 to theMFH apparatus 300.

In an analogous manner to that described above, the MFH apparatus 300can be vertically displaced relative to the wafer table 620 in order tocapture a film frame 30 carried by the wafer table 620 (e.g., a filmframe which has been held upon the wafer table 620 by a vacuum forceapplied to the underside of the film frame 30). In such a situation, thewafer table 620 need not maintain its application of vacuum force to thefilm frame 30 throughout the transfer of the film frame 30 to the MFHapparatus 300 (e.g., since film frame 30 lateral displacement along thewafer table surface 622 may be unlikely even in the absence of wafertable vacuum force), although the wafer table 620 can maintain theapplication of such vacuum force to the underside of the film frame 30in certain embodiments until, approximately until, or nearly untilvacuum force capture of the film frame by the MFH apparatus 300 iscomplete.

In view of the foregoing, once the MFH apparatus 300 has transferred afilm frame 30 captured or securely carried thereby to a givendestination, such as over an end effector 270 or the vacuum tablesurface 622, the film frame 30 can be transferred or offloaded to thedestination under consideration and released. When the offloaddestination is an end effector 270 or the wafer table 620, the MFHapparatus 300 will maintain its capture and secure retention of the filmframe 30 until secure capture of the film frame 30 by the end effector270 or wafer table 620, respectively has occurred (e.g., as determinedby way of a vacuum sensor coupled to the end effector 270 or wafer table620, respectively, in a manner readily understood by one of ordinaryskill in the relevant art). The MFH apparatus 620 can then be displacedaway from the offload destination (e.g., vertically displaced relativeto the end effector 270 or the wafer table 620).

Aspects of Representative Wafer Rotational Misalignment Compensation

Once a film frame 30 has been captured by the plurality capture arms310, the rotational misalignment compensation motor 340 can beselectively actuated to correct or compensate for rotationalmisorientation of a wafer 10 carried by the film frame 30. Suchmisalignment compensation occurs by way of the rotation of the entirefilm frame 30 relative to the pick and place z axis Z_(pp) in accordancewith a misalignment direction and misalignment magnitude or angledetermined for the wafer 10.

FIG. 13A is a schematic illustration of a film frame 30 carried by a MFHapparatus 300 in accordance with an embodiment of the presentdisclosure. In the event that the wafer 10 supported by the film frame30 is angularly misaligned relative to the film frame 30 by an extent orangle that exceeds a misalignment threshold magnitude value θ_(W-Max)(e.g., a maximum tolerable misalignment threshold, such as aprogrammable, selectable, predetermined number of degrees), themisalignment compensation motor 340 can cause the film frame 30 torotate in a direction opposite to the direction of wafer misalignment,and across an angular span, arc length, or number of degrees thatcorresponds to, equals, or approximately equals the misalignmentmagnitude determined for the wafer 10. When the MFH apparatus 300 placessuch a rotated film frame 30 upon the inspection system's wafer table620, the wafer 10 carried by the film frame 30 will have a correct orproper rotational alignment (i.e., a an angular misalignment ofapproximately zero degrees) with respect to the inspection system'simage capture device(s) 640. This correction of the wafer's rotationalmisalignment can correspondingly ensure that die 12 are properly alignedrelative to the image capture device's FOV 650.

In multiple embodiments, film frame rotation by the MFH apparatus 300occurs by way of the simultaneous or collective rotation of each capturearm 310 within the plurality of capture arms 310 about the pick andplace z axis Z_(pp), such as by way of rotation of the housing 302 towhich the capture arms 310 are coupled. In several embodiments, themisalignment compensation motor 340 provides, includes, or is coupled toa rotatable shaft 342 that is configured for rotating the housing 302;and a rotational motion encoder or rotary encoder configured forfacilitating or effectuating control over the direction and extent ofhousing rotation, in a manner understood by one of ordinary skill in therelevant art.

FIG. 13B is a schematic illustration of the MFH apparatus 310 rotatedabout the pick and place z axis Z_(pp) by a first misalignmentcompensation amount, magnitude, angle, or angular path length in a firstmisalignment compensation direction in accordance with an embodiment ofthe present disclosure, thereby compensating for or correcting a firstangular misalignment of a first wafer 10 a relative to a film frame 30.FIG. 13C is a schematic illustration of the MFH apparatus 310 rotatedabout Z_(pp) by a second misalignment compensation amount, magnitude,angle, or angular path length in a second misalignment compensationdirection, opposite to the first misalignment compensation direction, inaccordance with an embodiment of the present disclosure, therebycompensating for or correcting a second angular misalignment of a secondwafer 10 b relative to a film frame 30.

When a film frame 30 carrying a misaligned wafer 10 is carried by theMFH apparatus 300, rotation of the housing 302 across or by an anglethat equals or approximately equals the misaligned wafer's misalignmentangle θ_(W), in a direction opposite to the angular direction of thewafer's misalignment, compensates for or corrects the wafer'smisalignment, thereby establishing a correct or proper orientation ofthe wafer relative to one or more elements of the inspection system 600(e.g., an image capture device, and a FOV provided thereby). The rotatedfilm frame 30, and hence the correctly (re)oriented wafer 10 carried bythe film frame 30, can subsequently be transferred to the inspectionsystem 600. Furthermore, such rotation of a film frame 30 by the MFHapparatus 300 to compensate for wafer-to-film frame rotationalmisalignment can be performed while the MFH apparatus 300 is moving(e.g., “on the fly” film frame rotation during film frame transport),such as while the MFH apparatus 300 is transferring the film frame 300to the wafer table 620. Hence, following or during rotation of thehousing 302 by the first misalignment amount, magnitude, angle, orangular path length in the first misalignment compensation direction asindicated in FIG. 13A, the film frame 30 carrying the first wafer 10 acan be transferred to a wafer table 620 such that inspection can beginunder maximum throughput wafer die-to-FOV orientation conditions.Similarly, following or during rotation of the housing 302 by the secondmisalignment compensation amount, magnitude, angle, or angular pathlength in the second misalignment compensation direction as indicated inFIG. 13B, the film frame 30 carrying the second wafer 10 b can betransferred to the wafer table 620 for inspection.

Because a film frame 30 that has been transferred to the wafer table 620may have been rotated to compensate or correct for angular misalignmentof the wafer 10 supported by the film frame 30, in several embodimentsfilm frame registration operations occur away from the wafer table 620or off of the wafer table surface 622 (otherwise, any film frameregistration elements carried by the wafer table 620 would need to berotated or repositioned in accordance with the angular extent to whichthe film frame 30 had been rotated). Thus, in accordance with multipleembodiments of the present disclosure, a wafer table assembly 610 orwafer table 620 need not include, and can omit or exclude, film frameregistration elements or mechanisms, such as one or more film frameregistration elements 282 of a type described above with reference tothe first handling subsystem 250.

Furthermore, as indicated above, in some embodiments the MFH apparatus300 can determine and correct for the wafer misalignment angle θ_(W) inthe absence, omission, or exclusion of a film frame registrationprocedure (a) prior to film frame capture by the MFH apparatus 300, and(b) prior to the inspection system's initiation of film frame inspectionoperations upon a film frame 30 that the MFH apparatus 300 has directlytransferred to the wafer table surface 622 following any suchwafer-to-film frame rotational misalignment correction. As a result,such embodiments of the MFH apparatus 300 can facilitate or enable theelimination of such film frame registration procedures during film framehandling, thereby saving time and increasing throughput.

Aspects of Representative Film Frame Transfer

In various embodiments, the MFH apparatus 300 is configured to transferfilm frames 30 to the wafer table 620, such as by way of placing orpositioning film frames 30 directly upon the wafer table surface 622. Inseveral embodiments, the vertical displacement motor 350 is configuredfor vertically displacing the housing 302 across a particular orpredetermined distance in a direction parallel to each of the pick andplace z axis Z_(pp) and the wafer table z axis Z_(wt), to thereby placeor position the film frame 30 and its wafer 10 directly upon the wafertable surface 622. In such embodiments, placement of the film frame 30upon the wafer table surface 622 and/or retrieval of the film frame 30from the wafer table surface 622 need not involve, and can omit, avoid,or exclude the use of, wafer table ejector pins 612. After the housing302 has been displaced by a distance at which the film frame 300 underconsideration proximate, adjacent to, essentially upon, or upon thewafer table surface 622, a vacuum force can be applied by the wafertable assembly 620 to securely engage, capture, or retain the film frame30 and its corresponding wafer 10 upon or against the wafer tablesurface 622, in a manner understood by one of ordinary skill in therelevant art. In association with the placement of the film frame 30upon the wafer table surface 622 and the secure capture or retention ofthe film frame 30 thereupon, vacuum force(s) applied to the film frame30 by the plurality of component capture arms 310 can be released, andthe vertical displacement motor 350 can displace or raise the housing302, and correspondingly displace or raise the plurality of capture arms310 a given distance away from the wafer table surface 622.

Transfer of a film frame 30 held by the MFH apparatus 300 to the firsthandling subsystem 200 can occur in a manner that is analogous to thatdescribed above, for instance, by the first handling subsystem'spositioning of an end effector 270 coupled to a robotic arm 260 under orbelow the plurality of capture arms 310. While embodiments describedherein detail a MFH apparatus 300 configured for z-axis displacement,MFH apparatus embodiments in accordance with the present disclosure arenot limited to only z-axis motion.

Aspects of Representative Wafer Warpage or Non-Planarity Remediation

If a wafer 10 is warped, a next intended process to be carried out onthe wafer table 620 (e.g. inspection of wafer) cannot take place.Without manual intervention, the wafer inspection or manufacturingprocess will come to a halt, causing loss of throughput. Embodiments inaccordance with the present disclosure provide an automatic correctiveor remediative response when a wafer 10 is placed on a wafer table 620is automatically detected to be warped, thus eliminating or essentiallyeliminating the need for manual intervention and correspondinglyeliminating or effectively eliminating inspection system downtime orhalt-time caused by warped wafers 10, thereby increasing inspectionthroughput (e.g., average inspection throughput that isdetermined/calculated based upon a number of expected warped wafers 10within one or more inspection runs).

In association with and/or following the first handling subsystem'stransfer of a wafer 10 to the wafer table surface 622, the activation orapplication of a vacuum force by the wafer table 620 (e.g., by way ofactivating one or more vacuum values) is intended or expected tofacilitate secure engagement, capture, or retention the wafer 10 upon oragainst the wafer table surface 622 (e.g., by way of a vacuum forceapplied to the entire surface area of the underside of the wafer 10).However, when a wafer 10 includes one or more portions that arenon-planar, substantially non-planar, or warped, secure retention of thewafer 10 to the wafer table surface 622 may not be possible (e.g.,depending upon an extent of warpage). The lack of secure, suitable,sufficient, or appropriate engagement of a wafer 10 upon the wafer tablesurface 622 can be indicated by a determination of whether the magnitudeof an applied vacuum force or negative pressure (e.g., as automaticallyprovided or output by a vacuum gauge) is above or below an acceptablevacuum engagement pressure threshold value (e.g., which can be aprogrammable, selectable, or predetermined value).

In accordance with the present disclosure, multiple embodiments of theMFH apparatus 300 are configured for selectively applying or deliveringone or more vacuum engagement assistance, planarizing, flattening, ortapping (e.g., gentle tapping) pressures or forces to portions of awafer 10 supported by the wafer table surface 622, for which secure,adequate, or appropriate vacuum engagement to the wafer table surface622 cannot be established as a result of wafer non-planarity or warpage.In several embodiments, in response to an indication or determination(e.g., an automatic determination, as performed in accordance withprogram instruction execution) that the activation of one or more vacuumelements (e.g., vacuum valves) has not resulted in secure or adequatevacuum engagement of a wafer 10 to the wafer table surface 622, the MFHapparatus 300 can dispose the plurality of capture arms 310 overportions of the wafer 10, such that at least a portion of each capturearm's tip element 316 is positioned directly over or is capable ofengaging with or contacting a portion of an exposed, upper, or topsurface of the wafer 10 under consideration.

FIGS. 14A-14B are schematic illustrations of MFH apparatus positioningof capture arm tip elements 316 over portions of a wafer 10 tofacilitate secure capture of the wafer 10 upon a wafer table surface 622in accordance with an embodiment of the present disclosure. For a wafer10 under consideration, the positioning of capture arm tip elements 316in such a manner can dispose each tip element 316 proximate or adjacentto and/or overlapping with a peripheral or outer boundary or border ofthe wafer 10. For instance, each capture arm 310 within the plurality ofcapture arms 310 can be positioned at a radial distance away from thepick and place z axis Z_(pp) that is approximately equal to but slightlyless than the spatial extent, span, or diameter of the wafer 10 underconsideration. In a number of embodiments, the apparatus 300 can disposethe plurality of capture arms 310 such that (a) a circle whichintersects a center or central point of each capture arm's end segment314 is concentric or substantially concentric with a circular orsubstantially circular peripheral border of a wafer 10, and (b) eachcapture arm's tip element 316 can directly contact a peripheral portionof the exposed, upper, or top surface of the wafer 10.

The positioning of the plurality capture arms 310 over exposed portionsof a wafer 10 can define an engagement assistance configuration for thecapture arms 310 and/or their corresponding tip elements 316, inaccordance with which the MFH apparatus 300 can apply an engagementassistance force or pressure (e.g., downward force or pressure) toparticular areas or points of the wafer concurrent with the wafer tableassembly's application of a vacuum force to the underside of the wafer10, facilitating or enabling secure capture of the wafer 10 to the wafertable surface 622. One or more engagement assistance configurationsdefining spatial positions of capture arms 310 corresponding toparticular or different wafer dimensions, sizes, areas, or diameters canbe predetermined (e.g., in accordance with standard wafer sizes) andstored in and retrieved from a memory.

Following its positioning of the plurality of capture arm tip elements316 over exposed, upper, or top portions (e.g., peripheral or outermostportions) of a wafer 10 (e.g., in accordance with a particularengagement assistance configuration), the MFH apparatus 300 can displacethe capture arm tip elements 316 (e.g., by way of displacement of thehousing 302) in a vertical direction parallel to the each of pick andplace z axis Z_(pp) and the wafer table z axis Z_(wt), toward thesurface 624 of the wafer table 620. The tip elements 316 can therebyestablish contact with particular areas or points upon the wafer or filmframe surface, and apply an engagement assistance, flattening, orplanarizing force (e.g., a downward force or pressure) upon portions ofthe wafer 10. The wafer table assembly 620 applies a vacuum force to theunderside of the wafer 10 concurrent with MFH apparatus application ofthe engagement assistance force to the wafer 10.

As a result of the simultaneous application of (a) the engagementassistance force to portions of the top surface of the wafer 10, and (b)the vacuum force to the underside of the wafer 10, a non-planar orwarped wafer 10 can be automatically securely captured and subsequentlyretained upon the wafer table surface 622. Secure capture of the wafer10 upon the wafer table surface 622 can be automatically indicated ordetermined by comparing a current vacuum pressure reading, measurement,or value to a vacuum engagement pressure threshold value, in a mannerunderstood by one of ordinary skill in the relevant art. After securecapture of the wafer 10 upon the wafer table surface 622 has occurred,the MFH apparatus 300 can vertically displace the plurality of capturearms 310 away from the wafer 10, for instance, by raising or returningthe housing 302 to a predetermined, default, or waiting/ready position.

The aforementioned wafer handling process is particularly well suited toor enabled by wafer tables 620 having a wafer table structure 5 inaccordance with embodiments of the present disclosure, because thepresence of ridges 120 in such wafer table structures 5 enables vacuumforce to be confined and sealed beneath the portion of the wafer tablesurface area covered by the wafer 10. This effective vacuum sealprevents vacuum loss, and results in a strong vacuum force exerted uponor applied to the underside of the wafer 10, which in addition to thenatural suction force helps to keep the wafer 10 in the position atwhich it was placed on the wafer table surface 622. Without the ridges120, no effective vacuum force is likely to be activated because most ofan applied vacuum force would be lost through wafer table surface areasnot covered by the wafer 10.

In view of the foregoing, embodiments in accordance with the presentdisclosure can dramatically increase the likelihood that non-planar orwarped wafers 10 can be automatically captured and securely retainedupon a wafer table surface 622. Embodiments in accordance with thepresent disclosure therefore dramatically reduce or substantiallyeliminate the need for manual intervention associated with priorsystems.

Aspects of Representative Lateral Wafer Displacement Control/Prevention

As further detailed below, when handling a very thin wafer 10 by way ofa porous wafer table, a brief or very brief air spurt, burst, purge, orpuff is applied to the wafer 10 to facilitate release of the wafer 10from the wafer table surface. This can levitate the wafer 10 and causeundesirable, uncontrolled, or unpredictable lateral displacement of thewafer 10 across the wafer table surface 622. Such lateral displacementcan easily shift the wafer 10 away (e.g., significantly away) from apredetermined wafer load/unload position at which an end effector 270handling of the wafer is intended to occur. This can result inunreliable or unpredictable end effector 270 retrieval of the wafer 10,which can further prevent the end effector 270 from safely and reliablyinserting the wafer 10 into a wafer cassette or positioning the wafer 10at a subsequent processing station, quite possibly resulting in waferdamage or breakage.

In the past when wafers were thicker (e.g., on a normalized basisrelative to their surface area), it was possible to use ejector pins topush up from below the wafer to lift the wafer up against the suctionforce, especially when there were also grooves on the wafer table.However, if grooves are absent, the natural suction force upon the wafer10 can be very strong apart from the residual vacuum that may remainfrom the application of vacuum force through the wafer table 620. Thismeans that it is harder for the vacuum beneath the wafer 10 to escape.Moreover, today, wafers 10 being processed are much thinner. Given thesenew constraints, it is not possible to simply use ejector pins to pushagainst a thin wafer 10 held down by suction force. To do so would riskbreaking the thin and fragile wafer 10.

Porous wafer tables had previously been used in backlappingsystems/processes, but not in inspection systems/processes, until aninspection system such as that described in Singapore Patent ApplicationNo. 201103425-3, entitled “System and Method for Handling and AligningComponent Panes such as Film Frames and Wafers,” filed on 12 May 2011,included a porous wafer table 620 that can be used to handle wafers 10.However, it was discovered that facilitating the release of very thin orultra-thin wafers 10 from a very flat or ultra-flat porous wafer tablesurface 622 in a manner that reliably avoids damaging the thin andfragile wafer 10 during subsequent wafer handling can require humanintervention.

The description herein provides a solution to this problem. Tofacilitate the release of very thin wafers 10 from a very flat orultra-flat porous wafer table surface 622 in a manner that reliablyavoids damaging the thin and fragile wafer 10, a momentary spurt, burst,purge, or puff of positive air pressure is applied through the porouscompartment material in wafer table 620 to the underside of the wafer10. The application of positive air pressure releases the naturalsuction force and reverses any residual vacuum force beneath the wafer10. Once air is introduced beneath the surface of the wafer 10, theatmospheric pressure difference between the top and bottom surfaces ofthe wafer 10 will be equalized. However, this gives rise to yet anotherunique problem for wafer handling, which is the creation of an aircushion beneath the wafer 10 that causes the levitated wafer 10 to haveunintended and unpredictable lateral movement relative to the wafertable surface 622, as the air cushion may not be evenly distributedbeneath the wafer 10. The thinner the wafer 10 being handled, the morepronounced the effect that the air cushion has.

FIG. 15A is a schematic illustration of a representative wafer 10 thatis held uniformly against a porous vacuum chuck surface 40 by way of theaforementioned natural suction force plus a vacuum force or negativepressure applied to the underside of the wafer 10. FIG. 15B is aschematic illustration of the wafer 10 of FIG. 15A following vacuumforce cessation and the application of an air puff to the underside ofthe wafer 10, which results in the generation of an air cushion 42beneath the wafer 10. The presence of an air cushion 42 beneath thewafer 10 can cause the wafer 10 to slide laterally and unpredictablyalong the wafer table surface 622, depending upon wafer weightdistribution and/or differential support provided to the wafer 10 by theair cushion 42 underneath. FIG. 15C is a schematic illustration of thewafer 10 of FIG. 15B, indicating an unintended or unpredictable lateraldisplacement Δx of the wafer 10 along the wafer table surface 622 as aresult of the air cushion 42.

FIGS. 15D-15E are schematic illustrations of MFH apparatus positioningof capture arms 310 and capture arm tips 316 relative to a wafer 10 inmanner that limits or constrains wafer displacement along a wafer tablesurface 622 in accordance with an embodiment of the present disclosure.In several embodiments, following wafer inspection operations, the MFHapparatus 300 is configured for selectively disposing the plurality ofcapture arms 310 such that the capture arms 310 and/or capture arm tipelements 316 are positioned in accordance with a confinementconfiguration in which the tip elements 316 are disposed relative toeach other in a manner that defines a planar spatial confinement areathat is just marginally larger than the surface area of the wafer 10 onthe wafer table surface 622 for the purpose of preventing any lateralmovement. Vertical movement is not constrained.

When multiple capture arm tip elements 316 are (a) disposed inaccordance with a confinement configuration corresponding to a wafer 10having a given surface area A and a thickness t, and (b) touching thewafer table surface 622, or positioned at a distance away from the wafertable surface 622 that is significantly less than the wafer thickness t,each tip element 316 can be located just beyond the periphery of thewafer 10 and outside of the wafer surface area A. Such tip elementpositioning relative to the wafer 10 and the wafer table surface 622 canprevent or limit lateral displacement of the wafer 10 along the wafertable surface 622 beyond or outside of the spatial confinement arealaterally. Multiple confinement configurations can be defined and storedin and retrieved from a memory. Each confinement configurationcorresponds to a particular dimension, size, area, or diameter.

As a representative example, for a circular or generally/substantiallycircular wafer 10 having a given surface area A_(W) and diameter D_(W),a tip element confinement configuration can define or establish thepositions of tip elements 316 relative to each other, the pick and placez axis Z_(pp), and the wafer surface area A_(W) or diameter D_(W) suchthat a circle which (a) intersects a common point of each tip element316 that is closest to Z_(pp), and which (b) is concentric orsubstantially concentric to and slightly, very slightly, or marginallylarger than the wafer 10 defines a spatial confinement area A_(c) and acorresponding spatial confinement diameter D_(c), where A_(c) isslightly, very slightly, or marginally larger than A_(w), and D_(c) isslightly, very slightly, or marginally larger than D. Prior to theinterruption or cessation of vacuum or suction force upon the wafer 10,the MFH apparatus 300 can position the tip elements 316 in accordancewith this confinement configuration, such that each tip element 316 is(a) very slightly, slightly, or marginally beyond or outside of thewafer surface area A_(w), and (b) is in contact with or very slightly ormarginally displaced away from the wafer table surface 622. Followingthe interruption or cessation of a vacuum force applied to the undersideof the wafer 10, the wafer 10 will be unable or highly unlikely to movebeyond or outside of even during or after the application or delivery ofan air purge to the underside of the wafer 10.

Following vacuum force cessation or interruption and the application ofan associated air purge (e.g., nearly or essentially immediately aftervacuum force cessation), the capture arm tip elements 316 briefly remainin the confinement configuration, positioned upon or adjacent/proximateto the wafer table surface 622 to ensure that lateral displacement ofthe wafer 10 is constrained or prevented. After a predetermined timedelay (e.g., approximately 50 msec-250 msec or longer) and/or until theejector pins 612 are activated to lift the wafer 10 away from the wafertable surface 622, the capture arm tip elements 316 can be elevated awayfrom the wafer table surface 622, such as by vertical displacement ofthe housing 302 along the pick and place z axis Z_(pp).

Once the ejector pins 612 have lifted the wafer 10 to a final verticalposition relative to the wafer table surface 622, the first handlingsubsystem 250 can capture and transport or retrieve the wafer 10 to awafer destination 240. More particularly, an end effector 260 that ispositioned relative to the reference wafer load/unload position canreliably capture the wafer 10 supported by the ejector pins 612,reliably transport the wafer 10 to a next wafer destination 230, such asa wafer cassette, and reliably position the wafer 10 relative to thewafer destination 230 (e.g., within the wafer cassette) with minimal,negligible, or essentially no risk of wafer breakage due to wafermispositioning relative to/upon the end effector 260.

This process is particularly well suited when the wafer handling systemis processing a very thin wafer 10 to confine the wafer 10 to itsoriginal placement position, as very thin wafers tend to moveunpredictably with application of positive air beneath them.

In an alternate embodiment, lateral wafer displacement control orprevention occurs by way of a precisely timed wafer release and verticalwafer displacement process or sequence involving (a) the wafer tableassembly's cessation of vacuum force applied to the backside of thewafer 10; (b) the application of a brief air puff to the wafer'sbackside; and (c) the activation or extension of the set of ejector pins612 to elevate or raise the wafer off of the wafer table surface 622 ina manner that is precisely timed relative to air puff application orinitiation.

FIG. 16 is a flow diagram of a process 700 for limiting, controlling, orpreventing unintended, unpredictable, or uncontrolled wafer displacementalong a wafer table surface 622 in accordance with an embodiment of thepresent disclosure. In an embodiment, the wafer elevation process 700includes a first process portion 702 involving the positioning of thewafer table 620 at a predetermined, reference, or default waferload/unload position following completion of wafer inspection operationsduring which the wafer table assembly 610 applied a vacuum force to thebackside of a wafer 10 to facilitate secure retention of the wafer 10upon the wafer table surface 622.

The process 700 additionally includes a second process portion 704involving the wafer table assembly's cessation of the application ofvacuum force to the backside of the wafer 10, which is immediately,essentially immediately, or nearly immediately followed by a thirdprocess portion 706 involving the wafer table assembly's application ofan air puff to the wafer's backside from an air puff onset time to anair puff cessation time, the difference between which can define an airpuff duration. The air puff duration can be, for instance, approximately500 msec or less (e.g., approximately less than or equal to 250 msec).As a result of the application of the air puff to the backside of thewafer 10, residual vacuum force beneath the wafer's backside which maybe holding the wafer 10 against the wafer table surface 622 is released,and the natural suction force upon the wafer is also released.

The process 700 further includes a fourth process portion 708 involvingwaiting for a very brief ejector pin activation delay time following thetime at which the air puff was initiated and prior to activating ordisplacing the ejector pins 612 in an upward or vertical directionparallel to the wafer table z axis Z_(wt). The ejector pin activationdelay time is typically very brief. For instance, the ejector pinactivation delay time can be between approximately 5-50 msec (e.g.,approximately 10-25 msec) after the air puff initiation or onset time orwith a suitable time delay that can be determined experimentally.Immediately or essentially immediately after the ejector pin activationdelay time has elapsed, a fifth process portion 710 involves the upwardactivation or elevation of the ejector pins 612 to elevate the wafer 10away from the wafer table surface 600, and a sixth process portion 712involves lifting the wafer off of the wafer table surface 622 withminimal or negligible lateral displacement as a result of the very briefejector pin activation delay time relative to the air puff onset time(i.e., the time at which the air puff is initially applied to thewafer's backside). Finally, a seventh process portion 714 involvesreliably retrieving the wafer 10 from the ejector pins 612 using the endeffector 270.

As a result of the precise or highly controlled ejector pin activationtiming relative to the air puff initiation time, the ejector pins 612come into contact with the backside of the wafer 10 during an initialportion of the air puff duration, and lift or raise the wafer 10 awayfrom the wafer table surface 622 essentially or substantiallyimmediately after, or essentially or substantially synchronous with, therelease of the wafer 10 from the wafer table surface 622 in response tothe air puff. Because the ejector pins 316 are activated or elevated andengage with the backside of the wafer 10 following a very brief and wellcontrolled, predictable, or precisely timed interval following the airpuff onset time, it is expected that any lateral motion of the wafer 10that occurs prior to the ejector pins 612 elevating the wafer 10 awayfrom the wafer table surface 622 will be acceptably small, minimal, ornegligible. In a manner analogous or identical to that described above,an end effector 260 which is positioned relative to the reference waferload/unload position can reliably capture the wafer 10 supported by theejector pins 612, reliably transport the wafer 10 to a next waferdestination 230, and reliably position the wafer 10 relative to thewafer destination 230 with minimal, negligible, or essentially no riskof wafer breakage due to wafer mispositioning relative to the endeffector 260.

In certain embodiments, wafers 10 of different dimensions, sizes, areas,or diameters can exhibit different expected optimum ejector pinactivation delay times. Such different expected optimum ejector pinactivation times corresponding to different wafer sizes can bedetermined based upon experimentation or historical results, and storedin a memory or upon a computer readable medium for automatic retrievalby the control unit 1000 such that an appropriate ejector pin activationdelay time is selected in accordance with the current size of wafersbeing inspected.

Aspects of a Representative Wafer Handling Process

FIG. 17 is a flow diagram of a representative wafer handling process 800in accordance with an embodiment of the present disclosure. The waferhandling process 800 can be managed or controlled by a controller orcontrol unit 1000 (e.g., a computer system, computing device, orembedded system) by way of the execution of program instructions (e.g.,which are stored upon a computer readable medium such as a fixed orremovable RAM or ROM, a hard disk drive, an optical disk drive, or thelike). Such execution of stored program instructions can include thedetermination of whether a wafer 10 is securely retained upon a wafertable surface 622, and the retrieval from a memory or computer readableor data storage medium a vacuum force engagement threshold value andpossibly confinement capture configuration parameters.

In an embodiment, the wafer handling process 800 includes a firstprocess portion 802 involving retrieving a wafer 10 from a wafercassette using an end effector 270; a second process portion 804involving prealigning the wafer 10; and a third process portion 806involving transferring the wafer 10 to the wafer table 620 when thewafer table 620 is positioned at a reference wafer load/unload position.A fourth process portion 808 involves applying a vacuum force to thebackside of the wafer 10, and a fifth process portion 810 involvesdetermining whether secure retention of the wafer 10 by the wafer table620 has been established. Such a determination can include comparing acurrent vacuum or suction force reading or vacuum or suction forceleakage reading to a threshold vacuum force engagement value, in amanner understood by one of ordinary skill in the relevant art.

If secure retention of the wafer 10 by the wafer table 620 has not beenestablished within a given amount of time (e.g., approximately 0.5-2.0seconds), a sixth process portion 812 involves positioning the MFHapparatus capture arm tip elements 316 over peripheral portions of thewafer 10 while the wafer 10 remains upon the wafer table surface 622,and a seventh process portion 814 involves applying a downward forceupon such peripheral portions of the wafer 10 using the MFH apparatus300 while the wafer table 620 continues to apply vacuum force to thebackside of the wafer 10 to thereby establish secure capture orretention of the wafer 10 upon the wafer table 620. In certainembodiments, process portions 810, 812, and 814 can be repeated multipletimes, possibly with distinct or different rotational orientations ofthe capture arm tip elements 316, in the event that a first attempt toestablish secure retention of the wafer 10 upon the wafer table surface622 was not successful. Establishment of secure retention of the wafer10 upon the wafer table surface 622 in association with the sixth andseventh process portions 812, 814 can be determined by way of anautomatic comparison of a current vacuum force reading or vacuum forceleakage reading to a threshold vacuum force engagement value, as will beunderstood by one of ordinary skill in the relevant art.

Following the seventh process portion 814, or after the fifth processportion 810 in the event that secure vacuum engagement of the wafer 10upon the wafer table surface 622 occurred without MFH apparatusassistance, an eighth process portion 816 involves inspecting the wafer10. Once wafer inspection is complete, a ninth process portion 818involves positioning the wafer table 620 at the wafer load/unloadposition.

A tenth process portion 820 involves determining whether unwantedlateral displacement of the wafer 10 is to be limited or prevented usingthe MFH apparatus 300. If so, an eleventh process portion 822 involvespositioning MFH apparatus capture arm tip elements 316 in an appropriatewafer confinement configuration with respect to the wafer's diameter,and a twelfth process portion 824 involves disposing the tip elements316 in this confinement configuration upon the wafer table surface 622such that the wafer periphery is within the capture confinement areaA_(c) defined by the confinement configuration. A thirteenth processportion 626 involves terminating the wafer table's application of vacuumforce to the backside of the wafer 10 and applying an air puff to thewafer's backside, and a fourteenth process portion 628 involvesmaintaining the capture arm tip elements 316 in the confinementconfiguration on the wafer table surface 622 until rising ejector pins612 have engaged with the wafer 10 to elevate the wafer 10 away from thewafer table surface 622. While the capture arm tip elements 316 remainin the confinement configuration and are touching the wafer tablesurface 316, lateral displacement of the wafer 10 beyond the confinementarea A_(c) is prevented, thus ensuring that the wafer 10 remains at orapproximately at a predetermined wafer retrieval position to facilitatesubsequent reliable and damage-free wafer handling by an end effector270.

Once the ejector pins 612 have begun to lift the wafer 10 away from thewafer table surface 622, a fifteenth process portion 830 involves movingthe MFH apparatus 300 away from the wafer table 620 (e.g., by verticallydisplacing the MFH apparatus housing 302); and a final process portion840 involves retrieving the wafer 10 from the ejector pins 612 using theend effector 270 and returning the wafer to the wafer cassette.

Aspects of a Representative Film Frame Handling Process

FIG. 18 is a flow diagram of a representative film frame handlingprocess 900 in accordance with an embodiment of the present disclosure.In a manner analogous to that described above, a film frame handlingprocess 900 can be managed or controlled by the control unit 1000 by wayof the execution of program instructions (e.g., which are stored upon acomputer readable medium such as a fixed or removable random accessmemory (RAM), a read-only memory (ROM), a hard disk drive, an opticaldisk drive, or the like). Such execution of stored program instructionscan include the retrieval of maximum wafer-to-film frame misalignmentthreshold value from a memory; the determination of whether an extent ormagnitude of wafer misalignment relative to a film frame is less than orgreater than a maximum misalignment threshold value; and the retrievalfrom a memory a set of MFH apparatus capture arm positions correspondingto a film frame size under consideration

In an embodiment, the film frame handling process 900 includes a firstprocess portion 902 involving retrieving a film frame 30 from a filmframe cassette using an end effector 270, which applies a vacuum forceto peripheral portions of the film frame's underside, backside, orbottom surface. Some embodiments of film frame handling process 900 caninclude a second process portion 904 involving a mechanical film frameregistration procedure in which film frame alignment features arematingly engaged with a set of film frame registration elements 282. Forinstance, a registration element 282 can be carried by the end effector270, a portion of the MFH apparatus 300, a portion of a misalignmentinspection system 500, or a portion of the wafer table 620.

As previously described, in multiple embodiments, such a mechanical filmframe registration procedure can be avoided, omitted, excluded, oreliminated (in view of an optical or image processing based film frameregistration procedure), thereby avoiding or eliminating a conventionalfilm frame handling event or procedure, saving time, and increasingthroughput. Consequently, depending upon embodiment details, the secondprocess portion 904 can be omitted or eliminated, or the second processportion 904 can be optional in view of an optical film frameregistration procedure performed by way of the misalignment inspectionsystem 500 and the MFH 300.

A third process portion 906 involves determining a rotational or angulardirection and magnitude of wafer misalignment relative to the film frame30 using the misalignment inspection system 500. As indicated above,depending upon embodiment details, the determination of the angularwafer misalignment relative to the film frame 30 can occur (a) externalto or remote from the system 200, before the film frame 30 has beenretrieved by the end effector 270 in association with the first processportion 902; or (b) at any time following the retrieval of the filmframe 30 by the end effector 270 but prior to the initiation of filmframe inspection by the inspection system 600.

A fourth process portion 908 involves positioning the film frame 30beneath the MFH apparatus 300, e.g., such that a common axis of MFHapparatus capture arm rotation, such as the pick and place z axisZ_(pp), coincides with or extends through the center or approximatecenter of the film frame 30. A fifth process portion 910 involvespositioning the MFH apparatus capture arm tip elements 316 uponperipheral portions of the film frame's upper or top surface, andapplying vacuum force through the capture arms 310 such that the MFHapparatus 300 securely captures the film frame 30. A sixth processportion 912 involves terminating or releasing the end effector vacuumforce applied to peripheral portions of the film frame's underside, andmoving the end effector 270 away from the MFH apparatus 300.

A seventh process portion 914 involves rotating the film frame 30 usingthe MFH apparatus (e.g., by concurrently rotating the capture arms 310about the aforementioned common axis of capture arm rotation) in theevent that the wafer-to-film frame misalignment determined inassociation with the third process portion 906 exceeds the maximummisalignment threshold value, or in the event that a wafer-to-film framemisalignment was detected or determined. Such rotation occurs in adirection and through an angle that corrects the wafer-to-film framemisalignment, i.e., opposite to the wafer-to-film frame misalignment.

An eighth process portion 916 involves moving the wafer table 620 to afilm frame load/unload position, which can occur concurrently with theseventy process portion 914, thereby saving time and increasingthroughput. A ninth process portion 918 involves placing the film frame30 on the wafer table 620 using the MFH apparatus 300, such as by way ofvertical displacement of the MFH apparatus housing 302. The ninthprocess portion 918 can involve displacing the MFH apparatus housing 302by a predetermined distance, and/or determination of whether the filmframe 30 has been securely captured by the wafer table 620 inassociation with a tenth process portion 920 that involves applying avacuum force to the underside of the film frame 30 using the wafer table620. Once the film frame 30 has been securely captured by the wafertable 620, the tenth process portion 920 further involves terminatingthe application of the vacuum force applied through the capture arms 310to the top surface of the film frame 30 and moving the MFH apparatus 300away from the wafer table 620, thereby enabling subsequent film frameinspection. In particular embodiments, the ninth process portion 918 canadditionally or alternatively involve displacing the housing 302 towardthe wafer table surface 622 until the capture arm tip elements 316 touchthe wafer table surface 622, which can be determined by way of a set ofsensors (e.g., optical sensors).

An eleventh process portion 922 involves inspecting the film frame 30,and a twelfth process portion 924 involves positioning the wafer table620 at the film frame load/unload position. A thirteenth process portion926 involves positioning the MFH apparatus capture arm tip elements 316on peripheral portions of the film frame's top side, and applying avacuum force to the top side of the film frame 30 to capture the filmframe 30 while the film frame 30 remains upon (e.g., is securely heldto) the wafer table surface 622. A fourteenth process portion 928involves discontinuing the wafer table's application of vacuum force tothe film frame's underside, such that the MFH apparatus can capture andremove the film frame 30 from the wafer table 620.

A fifteenth process portion 930 involves moving the MFH apparatus 300,which securely holds the film frame 30, away from the wafer tablesurface 622, such as by way of vertically displacing the MFH apparatushousing 302. A sixteenth process portion 932 involves positioning theend effector 270 beneath the MFH apparatus 300, and a seventeenthprocess portion 934 involves capturing portions of the film frame'sbackside periphery using the end effector 270 by way of vacuum forceapplied through the end effector 270, such that the film frame 30 issecurely retained by the end effector 270 (and simultaneously retainedby the MFH apparatus 300). An eighteenth process portion 936 involvesdiscontinuation of the vacuum force applied to peripheral portions ofthe film frame by the MFH apparatus 300, such that the film frame 30 isreleased from the MFH apparatus 300. Finally, a nineteenth processportion 938 involves lowering the end effector 270 relative to the MFHapparatus 300 and transferring the film frame 30 back to the film framecassette using the end effector 270.

Aspects of various embodiments in accordance the present disclosureaddress at least one aspect, problem, limitation, and/or disadvantageassociated with existing systems and methods for handling wafers and/orfilm frames. Aspects of multiple embodiments in accordance with thepresent disclosure address each of the problems, limitations, and/ordisadvantages described above associated with existing systems andmethods for handling wafers and/or film frames. Moreover, multipleembodiments in accordance with the present disclosure improve waferand/or film frame handling in one or more manners that prior systems andmethods do not or cannot, such as by way of the elimination ofparticular handling events or procedures which results in enhancedthroughput. While features, aspects, and/or advantages associated withcertain embodiments have been described in the disclosure, otherembodiments may also exhibit such features, aspects, and/or advantages,and not all embodiments need necessarily exhibit such features, aspects,and/or advantages to fall within the scope of the disclosure. It will beappreciated by a person of ordinary skill in the art that several of theabove-disclosed systems, components, processes, or alternatives thereof,may be desirably combined into other different systems, components,processes, and/or applications. In addition, various modifications,alterations, and/or improvements may be made to various embodiments thatare disclosed by a person of ordinary skill in the art within the scopeof the present disclosure.

1. A system for handling wafers, each wafer having a periphery and asurface area, the system comprising: a wafer table assembly comprising awafer table providing a planar wafer table surface configured forcarrying a wafer, the wafer table assembly configured for applying anegative pressure or a positive pressure to an underside of the wafer;and a flattening apparatus configured for automatically applying adownward force to portions of a warped or non-planar wafer in adirection normal to the wafer table surface, wherein the flatteningapparatus eliminates a need for manual intervention when the warped ornon-planar wafer cannot be reliably retained on the wafer table surfaceas a result of its warpage or non-planarity.
 2. The system of claim 1,wherein the wafer table surface comprises a porous material. 3-35.(canceled)
 36. The system of claim 1, wherein the flattening apparatuscomprises: a main body positionable over the wafer table surface anddisplaceable along a vertical axis that is perpendicular to the wafertable surface; a plurality of arms coupled to the main body, each armwithin the plurality of arms having a tip element comprising a soft andresiliently deformable material coupled thereto, each arm controllablydisplaceable to multiple distinct positions transverse to and towards oraway from the vertical axis; a vertical displacement driver configuredfor (a) controllably displacing the main body and consequentlysimultaneously displacing the plurality of arms and the tip elementscoupled thereto along a vertical direction parallel to the vertical axisto position the tip elements in accordance with an engagement assistanceposition corresponding to a dimension of the wafer upon the wafer table,such that a portion of each tip element is disposed directly over anexposed upper surface of the wafer for engaging with or contacting aportion of the exposed surface of the wafer, and (b) controllablydisplacing the tip elements positioned in accordance with the engagementassistance position in a downward direction toward the wafer tablesurface.
 37. The system of claim 36, wherein the plurality of tipelements is displaceable to a plurality of engagement assistancepositions, each engagement assistance position disposing the tipelements away from each other across an area that is slightly less thana standard wafer diameter at the periphery of the wafer on the wafertable surface, wherein each engagement assistance position correspondsto a different standard wafer dimension.
 38. The system of claim 1,further comprising a displacement limitation apparatus configured forautomatically constraining or preventing uncontrolled lateraldisplacement of the wafer relative to the wafer table surface aftercessation of an applied negative pressure and/or an application of apositive pressure to the underside of the wafer via the wafer table, tothereby eliminate a need for manual intervention in response to suchuncontrolled lateral displacement of the wafer.
 39. The system of claim38, wherein the displacement limitation apparatus comprises: a main bodypositionable over the wafer table surface and displaceable along avertical axis that is perpendicular to the wafer table surface; aplurality of arms coupled to the main body, each arm within theplurality of arms having a tip element comprising a soft and resilientlydeformable material coupled thereto, each arm controllably displaceableto multiple distinct positions transverse to and towards or away fromthe vertical axis; and a vertical displacement driver configured for (a)controllably displacing the main body and consequently simultaneouslydisplacing the plurality of arms and the tip elements coupled theretoalong a vertical direction parallel to the vertical axis to position thetip elements in accordance with a confinement configurationcorresponding to a dimension of the wafer upon the wafer table, suchthat each tip element is disposed slightly beyond the periphery of thewafer, and (b) controllably displacing the tip elements positioned inaccordance with the confinement configuration in a downward directiontoward the wafer table surface.
 40. The system of claim 39, wherein thetip elements are displaceable to a plurality of confinementconfigurations, each confinement configuration disposing the tipelements away from each other across a planar spatial confinement areathat is marginally larger than the surface area of the wafer on thewafer table surface, wherein each confinement configuration correspondsto a different standard wafer dimension.
 41. The system of claim 38,wherein the wafer table assembly includes a set of ejector pinsdisplaceable along a vertical direction perpendicular to the wafer tablesurface, and wherein the displacement limitation apparatus comprises: acontrol unit configured for controlling: (a) an application of an airpuff to the underside of the wafer essentially immediately afterinterruption or cessation of the application of the suction force to theunderside of the wafer, the air puff applied from an air puff onset timeto an air puff cessation time; and (b) activation of the set of ejectorpins to displace the set of ejector pins in an upward direction after avery brief ejector pin activation delay time following the air puffonset time to thereby lift the wafer off of the wafer table surface withminimal or negligible lateral displacement as a result of the very briefejector pin activation delay time relative to the air puff onset time,wherein the ejector pin activation delay time is precisely controlledrelative to the air puff onset time such that the wafer is verticallyraised away from the wafer table surface synchronous with the release ofthe wafer from the wafer table surface in response to the air puff. 42.The system of claim 41, wherein the ejector pin activation delay time isexperimentally determined.
 43. The system of claim 41, wherein theejector pin activation delay time is between 5-50 msec.
 44. A method forhandling wafers, each wafer having a periphery and a surface area, themethod comprising: transporting a wafer to a planar wafer table surfacecorresponding to a wafer table assembly comprising a wafer tableconfigured for applying a negative pressure or a positive pressure to anunderside of the wafer; and automatically remediating insufficientretention of the wafer upon the wafer table surface due to wafer warpageor non-planarity.
 45. The method of claim 44, wherein automaticallyremediating insufficient retention of the wafer upon the wafer tablesurface comprises: automatically detecting insufficient retention of thewafer upon the wafer table surface; and responsively applying a set ofdownward forces to portions of an exposed upper surface of the waferconcurrent with the application of the suction force to the underside ofthe wafer to facilitate secure retention of the wafer upon the wafertable surface.
 46. The method of claim 45, wherein applying the set ofdownward forces comprises: positioning a flattening apparatus above thewafer, the flattening apparatus comprising a housing coupled to aplurality of displaceable arms, each arm within the plurality of armscoupled to a tip element comprising a soft and resiliently deformablematerial; positioning the tip elements in accordance with an engagementassistance position corresponding to a dimension of the wafer upon thewafer table, such that a portion of each tip element is disposeddirectly over the exposed upper surface of the wafer for engaging withor contacting a portion of the exposed surface of the wafer; anddisplacing the tip elements disposed over the exposed upper surface ofthe wafer downward toward the wafer table surface.
 47. The method ofclaim 45, further comprising: detecting secure retention of the waferupon the wafer table surface by way of a vacuum gauge; and terminatingthe application of the set of downward forces to portions of the exposedupper surface of the wafer in response to secure retention of the waferon the wafer table surface.
 48. The method of claim 44, furthercomprising automatically preventing uncontrolled lateral displacement ofthe wafer relative to the wafer table surface following interruption orcessation of the suction force and/or an application of positivepressure to the underside of the wafer.
 49. The method of claim 48,wherein automatically preventing uncontrolled lateral displacement ofthe wafer relative to the wafer table surface comprises: positioning aconfinement apparatus above the wafer, the confinement apparatuscomprising a housing coupled to a plurality of displaceable arms, eacharm within the plurality of arms coupled to a tip element comprising asoft and resiliently deformable material; positioning the tip elementsin accordance with a confinement configuration corresponding to adimension of the wafer upon the wafer table, such that a portion of eachtip element is disposed just beyond the periphery of the wafer;interrupting or terminating the application of suction force to theunderside of the wafer; and activating a set of ejector pinscorresponding to the wafer table in an upward direction to elevate thewafer away from the wafer table surface.
 50. The method of claim 48,wherein automatically preventing uncontrolled lateral displacement ofthe wafer relative to the wafer table surface comprises: interrupting orterminating the application of suction force to the underside of thewafer; applying an air puff to the underside of the wafer essentiallyimmediately after interruption or cessation of the application of thesuction force to the underside of the wafer, the air puff applied froman air puff onset time to an air puff cessation time; and activating aset of ejector pins corresponding to the vacuum table to displace theset of ejector pins in an upward direction after a very brief ejectorpin activation delay time following the air puff onset time to therebylift the wafer off of the wafer table surface with minimal or negligiblelateral displacement as a result of the very brief ejector pinactivation delay time relative to the air puff onset time, wherein theejector pin activation delay time is precisely controlled relative tothe air puff onset time such that the wafer is vertically raised awayfrom the wafer table surface synchronous with the release of the waferfrom the wafer table surface in response to the air puff.
 51. The methodof claim 50, wherein the ejector pin activation delay time isexperimentally determined.
 52. The method of claim 50, wherein theejector pin activation delay time is between 5-50 msec.
 53. A method forhandling a wafer in association with an inspection process, comprising:retrieving the wafer from a wafer source; transporting the wafer to awafer prealigner; disposing the wafer on a wafer table surface providedby a wafer table following prealignment of the wafer; applying anegative pressure to an underside of the wafer; automaticallyremediating insufficient retention of the wafer upon the wafer tablesurface due to wafer warpage or non-planarity by way of: detectingwhether the wafer is securely retained upon the wafer table surfaceprior to the initiation of the inspection process; and automaticallyapplying a downward force to portions of the wafer until secureretention of the wafer upon the wafer table surface is detected; andautomatically preventing uncontrolled lateral displacement of the waferalong the wafer table surface following the inspection process as aresult of cessation of the application of the negative pressure to thewafer by way of: (a) automatically confining the wafer to reside withina confinement position on the wafer table; or (b) coordinating thecessation of the application of the negative pressure to the undersideof the wafer with an application of an air puff to the underside of thewafer and an activation of a set of ejector pins that is verticallydisplaceable relative to the wafer table surface, such that the wafer isvertically raised away from the wafer table surface synchronous with therelease of the wafer from the wafer table surface in response to the airpuff; and retrieving the wafer from the wafer table and transferring thewafer to a wafer destination.